From Wiktionary, the free dictionary
phá (“破, to ruin; destroy; dispel”) + bĩnh (“poop”).
phá bĩnh
- (colloquial, dated) to disrupt; to interrupt; to be a killjoy (toward); to ruin (a situation; especially of a good time)
- Tôi không muốn làm kẻ phá bĩnh. ― I don't want to be a killjoy (...a jerk to be a killjoy).