Please share your discoveries over the secrets and easter eggs of the past :
In Zak McKracken, at your boss’ office (in the game’s intro), you can see a picture with two aliens.
The same picture can be found in an art gallery room of Indiana Jones 3 nazi castle !
On the plaque of the naked statue in Maniac Mansion (actually a real statue, look up Michaelangelos “Dawn”) it says in french “property of the louvre, return when found, postage payed” implying on top of it all the family are art thieves, too!
I’m not sure that after all these years we can still call these things “secrets”, but I’ll share one nonetheless. 
In “The Secret of Monkey Island” Guybrush can really die, if he stays more than 10 minutes underwater.
It wasn’t until last year that I found out you can play the ‘knife game’ in Full Throttle if you bug Emmet enough times. Fun!
I’d always save my game and do this, because it was sorta gross and the verbs were funny as I recall
The stump joke.
In MI1, but only in the floppy versions, when you look at a particular stump in the forest, Guybrush discovers a tunnel leading to a dungeon underneath it. Unluckily the game asks then for a floppy disk you don’t have, and, after many tries and silly request, Guybrush gives up, stating “I can’t play that part of the game”.
Too bad the joke was removed from the later versions, but it was quoted by the debs of MI3: when you are inside a tomb, you look at a crack in the wall, and you find Guybrush’s head popping out of that MI1 stump… nice, indeed.
Yeah that was the “please insert floppy #22” joke!
In CoMI, you can give gum to Murray and he blows bubbles lol.