When I was a kid, I was absolutely convinced that if I ate a watermelon seed, a watermelon tree would grow in my stomach. I’m not sure if my dad or my grand-dad was the one to sow that particular notion in my head, but both of them definitely hinted at the fact that it was true. For years I lived in fear of turning into some child-beanstalk hybrid. I vividly remember waking up in the middle of the night once, convinced that the tickle in my throat was the beginning of a watermelon tree growing up and up through my digestive tract. I don’t think I realized until I was in middle school that watermelons neither grow on trees nor have the ability to sprout in my stomach.

A recent Twitter thread sparked by a tweet from writer and Slate parenting advice columnist Nicole Cliffe reminded me not only of that particular childhood fear but also the ingenuity of parental lying.

We had so many great months of the kids thinking that Scooby Snacks were plain whole wheat crackers, and then a babysitter bought a box of Scooby fruit snacks and the whole system collapsed in under three minutes. — Nicole Cliffe (@Nicole_Cliffe) January 23, 2018

A lot of the little white lies that emerged in the discussion were centered around kids and food, like this mother who convinced her daughter that there was a “‘body surface area ratio’ rule for candy such that the bigger body surface area you had, the more candy you could eat,” allowing the mom to claim the majority of her kid’s candy. Or this mom and dad who have their 7-year-old convinced that mozzarella sticks are only sold at vacation spots. Some of them are just pure trolling, like this dad that for some reason told his kids that every herd of cows has a member named Herman.

These sorts of silly ideas are easily shed with age. However, one lie that showed up in the discussion seems to be strangely strong and ubiquitous, to the point where many people believe it well into adulthood: that having lights on in your car while driving is illegal.

my mom convinced me that it's illegal to keep the lights on inside the car when you're driving, which I only found out was a lie about three years ago. — merrite (@merrite) January 23, 2018

wait I am sure this is true https://t.co/Pzce0q40fZ — Nicole Cliffe (@Nicole_Cliffe) January 23, 2018

To be clear, this is not true. Driving with internal lights on is definitely hazardous, in that it can reduce external visibility for the driver, but the whole point of map lights are that someone in the passenger seat can navigate while someone else is driving. To date there’s no law on the books in any state or federally that prohibits driving with lights on. Of course, it’s easy to see why parents might lie and claim the opposite: It’s a well-known fact that kids like buttons, and explaining to your 5-year-old the concept of reduced night vision while you’re in the 13th hour of a road trip sounds like the third ring of hell.

Even so, parents should be careful. The car lights lie reminds me of one of these that my friend’s parents told her. To keep her from opening up the liquor cabinet as kid, they told her that the particular living room enclosure was booby-trapped and that an alarm would go off if she ever opened it up. For years she lived in terror, walking on eggshells in her own living room, until she was 16 and asked her mom for the code to the cabinets so she wouldn’t get zapped. By that point, her mom had forgotten she had ever even lied about it.

Of course, these sorts of lies are all pretty harmless (and often funny as hell). But stories like the car lights and the forbidden cabinet also offer a lighthearted rule for parents to consider before they toss off a lie to their kids: Think hard about potential repercussions, because you never know what’s going to stick.