You know who you are. See also Hippies.
Psst. Got something funnier? Add your own funny thing to do.
The abandoned and now discredited practice of parents gathering children around a child known to have chicken pox and, among other methods to spread the infection, sharing lollipops. The theory was that chicken pox is less dangerous to children than adults, and should be encountered as early in life as possible. See also 70's.
And see who looks up. Sadly, I fell for this the first time. See also Pranks.