Team Kills:

TEAAAM KILL HAACK !!!

Why do you want team kills? LMAO

Have fun killing ur team with nade./

Nade them only

Yeah lmao tk them and they'll cry

i have 20k team kills , lool

Throw grenades at team mates with low health

Method 1:
Get a clan/party/friends to nade team mates. Preferred game mode: Something round-based.

Method 2:
Go on S&D and follow team mates and wait until they get a kill, usually they will get hit by then. At that time throw a nade at that team mate. Some times works, sometimes does not.

Method 3:
Unlimited Grenades

Method 4:
Friendly Fire hack ( it's possible with a lot of work studying Cross Fire )

(Worst) Method 5:
Randomly throw grenades in TD where you think they will land at a team mate.

Method 4 is the most efficient
Method 2 or 1 is the easiest I'd say
Method 5 for lazy people.