There are probably a couple scenarios here:
1) Taco Bell victim had previously been "entertaining" his dining partner and, by extension, the rest of the patrons dining in the establishment with his Baja Blast induced burping skills. After hearing a half dozen or so juicy, resonant blasts, the perpetrator used the lack of manners and continued lack of consideration and reflection as an excuse to enact swift South of the Border Justice on the belcher.
2) Bath salts.