It doesn't especially, I suppose.
There are a few jokes and things on prints and decals though.
A lot of the default Face Decals come from Memes.
The Spray-Can has a joke written on it's label.
The PC Monitor Print has the Blockland Forums on it, and it has joke numbers on it. The time on the PC clock is 6:66, and the number of messages the user has is 666, I think.
And back when Maps were around, there were easter eggs in those.
There were a few hiding places and secret paths in the Kitchen and Bedroom.
And the clocks in both would explode when they rolled over 99:99, if I recall correctly.
And I think it was possible to blow up the lightbulb in the lamp in the bedroom, but I'm not sure.