Chances of pregnancy

What do you guys think the chances of a possible pregnancy or (having sperm contained in precum) would be if you just put a man's penis in you for one "thrust" with precum on it, when he hasn't masturbated in 5+ days. I haven't done it, but I'm curious to hear you girls' thoughts!!! (BTW with no birth control methods at all and completely suceptible to getting impregnated)