Who remembers ...?

A well known antiSocial Networking site, from time to time, throws up a photo with a caption along the lines of :-
"Like if you know/remember what it is.
Share if you have one."

Once upon a time: you couldn't buy a bottle of any medicine, over the counter, without one of these on the cap. Now, you'd probably find it impossible to buy one with such an adornment.
Being a hoarder, I can usually lay hands on one or two in "That Drawer".