I used to love this one as a kid, but I can no longer remember the lyrics. I think it was recorded by a popular "folk" group like the Irish Rovers or somebody.

The chorus is:

Doon in the wee room,underneath the stairs, Everybody's happy, everybody's there, And we're all makin' merry, each in his chair, Doon in the wee room, underneath the stairs.

Much obliged.