Whoever clogged the toilet in the restroom above this H&M but kept flushing anyway REALLY made a damn mess for the store ... and no, this can't be good for holiday sales numbers.
Folks at the Times Square H&M location tell TMZ ... there was a major plumbing issue Friday in the ceiling above the store, and eventually the water leaking from the faulty pipes was too much weight to bear.
Check out the video ... whoever was filming thought it was all fun and games -- until it became cleanup on aisle, well, everywhere.
We're told the good news for the store is the issue has been resolved, the damage has been fixed ... and shoppers can resume purchasing its reasonably priced holiday pajamas and sweaters.