A joke from Phanwank, "masterful virgin" refers to the commonplace badfic technique of making Erik's first time the Super Bowl of Sex, thereby preserving in the phangirl's mind the fantasy of a genius so hot, needy, and misunderstood by others that only she could possibly understand him and facilitate his absolute pwnage of the female body. Oddly enough, this term seems to apply to a lot of characters on the Verse.
This is based on a misunderstanding which seems to be endemic only to Phandom. Men living in basements for decades probably have great familiarity with sexual organs. Just not other peoples'.