be on (one's) ass(redirected from be on his ass)
be on (one's) ass
1. slang To be driving too close to another car. Primarily heard in US. Why is this guy on my ass when I'm already going over the speed limit?
2. slang To be a constant critical presence in someone's life. Primarily heard in US. My mother has been on my ass this entire visit, questioning every aspect of my life from my marital status to the improper folding of my linens.