I mostly wear jeans.If it's dress slacks I've always made sure they're a safe fit.But I hear duct tape is a good(justincase)patch(on the inside of course)
If they split while I was bending over, I would be embarrassed and seek privacy as quick as I could. If I had a sweater or something I would tie it afround my waist.
If it was torn somewhere else I would just live with it.
This happened to me when I was bartending when I was bent over rotating beers in the cooler -- major embarassment -- I had to tie two bar towels around me at the hips until daughter brought me different pair. Men can be so crude sometimes ...