I recently had an encounter with another man whom I didn't know. It was very very brief - in a shower - and consisted of hand-to-genital contact and I received oral sex (his mouth on my genitals) for about 20 seconds without ejaculation. How worried should I be about possible STI/STD infection given that the encounter was so brief, and I was on the receiving end? If testing is necessary, how long should I wait before possible STIs are detectable?