If it was a guy. Probably be tempted to مککا, عجیب الخلقت his lights out. He doesn't know my sexuality yet he randomly kissed me. It's disrespectful. If I don't مککا, عجیب الخلقت him. The death glare will be given.
If it was a girl I didn't like and she kissed me. I'd give her a death glare to enforce that it was disrespectful and not to do it again.
If it was a girl I actually was attracted to and she kissed me randomly. I'd be in shocked and then ask her why did she do it. Based on that answer I'd proceed further.
if a random guy kiss me, ill be super angry obviously...but مزید than me, the people around me, if they see it, they will make a big scene out of it... if a couple kiss in public itself , people will stare at them and will make weird face :P