It doesn’t rely on quirky, regional or any kind of accents to be funny.
It’s basically Seinfeld in one scene.
Doesn’t rely on swearing.
The sexual references are not intended to be vulgar, crude or crass.
Avoids obvious gags – most of the time you have to think about the humour.
In a single situation the three companions ruminate on a strange (or not so strange) situation, while being in a seemingly enclosed situation of their own (lasting 15 minutes).
What’s going on in the background is equally as important as what’s taking place in the foreground.
You can put them in ANY situation and they’lll end up debating something!