Can you tell me can i catch aids from a bj?

Unlikely: Performing oral sex on a man carries some risk though it is far, far less than receptive anal intercourse and much less than vaginal intercourse. If you're going to be in this situation, a condom is a great idea.

HIV is Hard to Get: Yes. The third most common way HIV is transmitted sexually is by being the receptive partner performing oral sex on an infected male. The risk is about 1 in 20, 000 encounters. So it is very rare. But, yes, it is possible.