new members (e.g. club); new students; freshman; event to welcome new students, club members, etc. (e.g. welcome party)
exchange of courtesies (cordialities); fraternization; fraternisation
party to welcome (e.g. new employees) and send off (e.g. retiring employees)
joys and sorrows; happiness and sadness
to enjoy oneself to one's hearts content; to enjoy oneself to the full
enjoying pleasure together