SisQó Downsizes 'Thong Song' ... and It's Just Sad

3/29/2013 10:45 AM PDT

SisQó -- Downsizes for 'Thong Song' ... and It's Just Sad


"She had dumps like a truck truck truck ... "

In the mood now? Good ...'cause we got SisQó performing his giant, monster, ENORMOUS hit, "Thong Song" last night -- which is HUGE -- but where he performed it is the real story here.

We found the R&B star doing his signature song from 2000 in Washington, DC suburb ... Alexandria, VA. But not in an arena -- a sports bar. A REALLY cramped, small sports bar.

You gotta see the video ... 'cause poor SisQó has to dodge bouncers and waitresses just to do a dance move.

Reminder ... "Thong Song" went all the way to #3 on the charts ... and SisQó used to perform it to sold out arenas with thousands of people singing along, "That thong thong thong thong thong!"

Things change.

Fun fact (for everyone but Sisqó): "Thong Song" was blocked from #1 by ... Santana's "Maria Maria."