mike- he was taking you home after a date and he kissed you
will- he invited you over and johnathon dared both of you to kiss each other so you did.
lucas- at the snowball
dustin- the two of you got excited after completing something and just kissed
steve- after he asked you out
johnathon- the two of you were taking a walk through the woods for no apparent reason and kinda just kissed
billy- your first date
eleven- after asking her out
max- billy was making out with his girlfriend so the two of you tried it out
nancy- on your 2nd date
robin- steve told her to kiss you when you visited her at work
henry/peter- in his room after a week of dating
eddie- before a hellfire club meeting
chrissy- after cheer practice
fred- he invited you over to study, but you got bored and kissed him