Lisa Lampanelli Explains Why She Went Off on Heckler

Lisa Lampanelli does NOT like being interrupted at work -- that much she made clear to us while explaining why she went nuclear on a heckler during her stand-up set this weekend.

We spoke to Lisa a day after her meltdown in San Jose during a show she was putting on -- where a guy offered her $100 to "shut the f*** up" ... which made her flip.

The insult comic says the man interrupted her while she was having a convo with someone else in the audience -- and, apparently, Lisa doesn't like that very much. She then directed her attention to the bloke ... and things went downhill from there.

Lisa says she doesn't like pegging incidents like this on sexism but, in this case ... she thinks it's pretty clear the heckler felt empowered because she was a woman.

Well, that wasn't gonna fly with Lisa -- she's been around too long for that BS ... according to her, anyway.