"My father used to tell my sister that he bought her at a Walmart like store for $25."
"My brother convinced a group of like 9 year olds that he was the moon's lawyer once."
"My daughter, when she was six, I convinced her that swallowing a mentos would grow a mentos tree in your stomach... One day I accidentally swallowed one in the car, had a discussion with my wife about "oh, I'm sure I'll be fine, etc etc" then let it sit a few days.
Used her bathroom a few days later. After I flushed, I threw a couple dead leaves on the toilet...
Waited a couple more days...
Woke her up for school with a twig placed behind my ear...
Waited a couple more days...
Woke her up with a branch sticking out of my mouth and me "screaming" for her to remove it... She looks at me, screams "MOOOOOOMMMMMM!!! DADDY NEEDS A DOCTOR! A DOCTOR MOM!!!!" and runs out of the room...
Best part is she was nine before she finally realized it was all a joke. Her friends all believed I had a tree in my stomach... I found out she took the twig from behind my ear to show and tell that week and the teacher didn't have the heart to tell her it was a joke. She just believed it so much. She's fifteen now and loves this story... Good times."
"I convinced my sister that she was originally an origami dolphin, and my mom wished really hard she turned into a little girl (a Pinocchio-esque situation). She cried and asked my mom, who went along with my story. Sis believed for years that she used to be an origami dolphin."
"We convinced my younger brother that those giant bales of hay wrapped in white plastic were marshmallows on the marshmallow farm.
Which he believed until he was about 18 or so, when he angrily came home after embarrassing himself in front of his friends and got mad at us for lying to him about the marshmallow farms."
"That if you sit quietly in the car, it makes the car go faster so you'll get there quicker. This one worked on me for an embarrassingly long time."
"Not exactly a lie, but I taught my kid to jump up, do jazz hands and yell "Tada!" whenever she fell down as a toddler. She'll come tearing down the sidewalk, trip, skid a few feet, and then pop up, a little shaky, and say "Ta...(deep breath) Daaaaaa..." I feel bad every time I laugh at this."
"When I used to babysit I would tell the kids that the popcorn wouldn't pop unless they started jumping. They would always say "nuh-uh" but with popcorn it takes a about 30 seconds at least to start popping. I would say, "it sure does, watch" and commence jumping. POP POP POP. They're eyes would get huge. I'd feign getting tired so they would help, and I wound up with a kitchen of 3 and 4-year-olds jumping for a few minutes until movie time. During which they would usually fall asleep, and I would get to work on homework. :)"
"Sleeping with different blankets give you different dreams. Got nightmares? Change the blanket."
"I live in south-central TX and we have a place on the coast, I've made the trip there & back hundreds of times at this point in my life. When we were small kids doing the drive down late one night, my uncle told us that the incredibly large, well-lit and operational refineries and chemical plants we were passing were outsourced factories full of Santa's elves churning out presents shortly before Christmas. 10/10 would fall for this lie again, it added a nice layer of wonder to that part of my life."
"Whenever a kid at work tells me they have a loose tooth, I tell them I have a loose foot, then I wiggle my foot around. I tell them I think my foot's going to fall off soon, but it's ok because it's just my baby foot, and my grown up foot will come in soon. I'll put my foot under my pillow, and the Foot Fairy will bring me a dollar for it.
If they say something like "That's not true! It's just teeth that fall out, not feet!" I'll say "Well, why is my foot so wiggly then?" and wiggle it some more."
"My dad had some good ones: Toys R Us is a museum, so no, we can't bring anything home. All the animals at the zoo are different kinds of dogs."
"My teacher girlfriend told her class that the smoke detectors were CCTV cameras. Every time one of them obviously lies, she goes "Well I'll just go check the tapes and see who's right", and they fess up. Works every time."
If a kid asks where rain comes from, I think a cute thing to tell him is "God is crying." And if he asks why God is crying, another cute thing to tell him is "Probably because of something you did."
"When I was younger and spent my weekends at big arcades, I would often play this one rail shooter game that required you to sit in a chair in a big plastic sphere. I would often tell the kids waiting in line, "If you die in the game, you die in real life". The looks of horror fuelled me for years."
"I had my three year old niece convinced I'm six years old, just super tall, for a bit this weekend. That was pretty funny."
"I have large, sharp canine teeth. My nieces have flat canines. I told them this is because I'm a werewolf, and when they turn 10 (twins), I will choose one of them to pass the curse on to. This started when they were around 3 -4, and they are just starting to really question it at 8, but the fact that my mother and sister agree with every aspect of my story is really confusing them. I'm going to start using fake blood and other props to reinforce it."
"Told my sister that humans start lives off as dogs. It was so funny, she waited patiently for our dog to turn into a human so she wouldn't be the youngest."
"When I was a kid my parents convinced me that if you pour salt on a bird's wings they can't fly. I spent years chasing birds after dinner in the summer (never succeeded). My parents told me it was some of the funniest shit they've seen in their lives."
"My buddy tells his daughter about all the different princess' he used to date, until she figures out which Disney movie he's referring to."