I found this answer from THIS web page (I believe it to be correct, but I'm not sure):Originally Posted by atrassato
"Jaxx" is a clever way of spelling "Jacks". The meaning of "jack" in this context is the type of dancing one does to house music. I think it had a lot more meaning in the early days of house and not many people use it now, but most people that are really into house music know what it means. You might have heard the phrase "jack your body". It just means dancing to house (though I'm not sure if there's any signature moves or exactly how to do it).
So Basement Jaxx means jacking in the basement. If you have the Jaxx's 1999 Essential Mix they play an acapella (that they've used in other mixes here and there). It's a woman speaking and it goes something like this:
Come on baby, jack.
Come on baby, jack yo' ass.
Jack yo' ass, goodness! Move your ass.
You ain't jackin', you ain't livin'!
Can you jack? Can you jack?
I wanna see you jackin'!
I feel good tonight!
I'm not a teacher, so please consider any advice I give in that context.