To join in, to take part, to involve oneself (in something).
To act as part of, or on behalf of, a squad.
Sloppy mud.
One's friend group, taken collectively; one's peeps.
A unit of tactical military personnel, or of police officers, usually of about ten members.
A group of potential players from whom a starting team and substitutes are chosen.
A collective noun for a group of squid.