What would happen if someone had oral sex with someone that has a urinary tract infection?

Nothing: Generally the bacteria that cause typical urinary tract infections do not cause mouth or throat infections. However make sure they do not have an infection like gonorrhea or chlamydia which can feel like a urinary tract infection but can be transmitted by oral sex.

Not much: Unless recipient also has std. Would not think it all that pleasant if it was the recipient who had the uti. Why not wait until the UTI has been successfully treated?