My favorite drunken-singing material is, as follows :
1."Runaway" by Del Shanon - EVERYONE knows this song!
2.& 3."The Great Pretender" and "House of the Rising Sun" - a friend once asked me to play one to the chords of the other, it can still be a chalenge if I'm drunk enough.
4."Wish You Were Here" played a lot faster with SRV style guitar accompaniment. I do slow it down at some point to let everyone get comfortable with it.
5.Blues version of "Enter Sandman" - I like to play songs differently and this one is a perfect fit.
We also sing songs with only one wovel, songs beginning with the same letter, songs containing a name of a girl or an animal or whatever.