If the boy ejaculated and his semen seeped through the boxers while they were touching the girl's vagina, there's a chance that some sperm made it into the vaginal opening and up the fallopian tubes. It's possible, just not very likely.
Can A Girl Get Pregnant If She Was Naked And The Boy Had Boxers On?
You can if semen entered your vagina.
Yes if the semen got out
Very unlikely since it dies off in seconds