I can't speak for others... but Simon of the Chipmunks is a well read kid. he knows a lot about a lot, and clearly has studied drugs and drug abuse. Not to mentioon Dave might have had a serious talk with the boys, like all parents should have.I have and he says the same that I do: How can cartoon characters from our childhood know what drugs are?
As for the TMNT, they have ALWAYS had a hard stance on Drug abuse. From the infamous "I'm no chicken, you're a turkey" PSA, to the sequence in the movie where Danny the Runaway puts painkillers on top of a Pizza, forcing Mike and Don to sadly toss it out... even to T-Shirts and at the beginning of their Arcade game.
And apparently the A Pup Named Scooby Doo characters know what they are... while they didn't appear in an episode, one of the villains in the show either abused or delt drugs. I forget which episode, and to what extent... and it was just mentioned. But what I can clearly remember, Scooby Doo mutters "Drugs! Yuck!'