Is it impossible to have an std if youve never had sex?

Possible but nlikely: While it is possible to transfer an std via non-genital contact, it is not likely.

Very unlikely: It wouldn't be easy. Theoretically you could get an oral std from kissing someone who had one, but i frankly have never seen such a case. With very rare exceptions, STDs are diseases of sexually active people. (i'm assuming that when you say "sex, " you're not just talking about intercourse.).