A few times actually.
Every Friday night I watched this 8 year old girl and she was a mega brat. Well one week she was suffering from allergies so her mom told me to give her benadryl if needed. I noticed that when she took it she was out by 9 pm when most nights she didn't fall asleep until 11 or 12 and even then she wasn't in a deep sleep.
So from then on I would make her special smoothies. She would make most of it with me then I'd have her go to the living room while I put the secret ingredient in there(sunny delight and benadryl)
I would then tell her we were going to have a contest on who could drink it the fastest. So she drank every last bit then she was out and I could relax for the night.
*shrugs* it never hurt her.
oh and not sure if it makes a difference but i was only 16 when i did this.