From TF2 Wiki
Griefing is the act of using or abusing a game mechanic in ways originally unintended by the game's developers for the specific purpose of angering or otherwise negatively impacting the game experience of another player. Griefing can sometimes be difficult to pinpoint because its defining characteristic is intent and not action.
Griefing is distinctly different than "being an idiot." Bug abuse and hacking can be griefing, but only when done specifically to disrupt another player's gameplay, and not when done simply to gain an unfair advantage.
List of acts that are never griefing
- Camping. Camping things like spawn points and Teleporter exits, while not technically griefing, is still frowned upon.
- Rooting out Spies, Engineers, or other classes hiding behind the team
- Killing the same player repeatedly in order to remove a tactical advantage gained by their presence from a defensive or exposed location
List of acts that may be griefing
The following are griefing when they are done to disrupt someone's enjoyment of the game:
- Mic spam
- Text/call spam
- Bug abuse
- Repeatedly stealing Teleports from slower or more vital classes
- Faking a trade deal that would be considered good eg. earbuds for 2 hats.
List of acts that are almost always griefing
The following items are almost always griefing, because it is generally the only reason to do them:
- Pushing players of ledges so that they have to waste time getting back up or killing them.
- Intentionally healing enemy Spies so that they are able to kill your teammates.
- Intentionally ÜberCharging enemy Spies so they can kill your teammates.
- Intentionally and repeatedly healing disguised friendly Spies in order to disrupt their cover.
- Building teleporters in between another engineers sentry and dispenser so that they cannot stand in the ideal spot without being teleported away. (usually backwards)
- Using Teleporters to trap your team-mates in inescapable locations.
- Deliberately placing teleporter across vital exits and entryways so it is impossible to pass them without being teleported (usually back to your spawn).
- Placing teleporter that lead to a useless areas or just a few feet away from the entrance.
- Continuously obstructing a Sniper's view by staying in front or using a flamethrower to cover Sniper's scope.
- Repeatedly killing the same player, and only the same player, in order to annoy them and with no tactical reason for doing so.
- Exploits, such as Skywalking in Dustbowl (Stage 3, Control Point 2) with the express idea in mind to annoy/anger the enemy team.
- Setting up Sentries and Dispensers in areas that the enemy cannot reach in order to irritate your team-mates; for example, at the BLU team's setup/respawn area in Gravel Pit.
- Putting teleporter exits in inescapable or immediately hostile areas.
- Intentionally being worthless to your team. For example, standing in the same place, only using melee weapons, and running straight into enemy fire.
- Attacking your own teammates for long stretches of time for no reason besides annoying them.
- Following the same teammate around for no reason.
- Übering teammates for no reason, such as Übering a Sniper that is in no danger, Übering teammates in the spawn, etc.
- Building teleporter exits in your own base and placing the entrance in the enemies, allowing for spy infiltration.
- While you are playing as Soldier, Intentionally calling for Medic with the Equalizer out, even when you are not injured.
- Building teleporter entrances in direct path of a sniper's strafing route (such as the battlements in 2fort) that go backwards and/or are counter productive
Team Roomba: Griefing
These are some examples of griefing, made by TEAM ROOMBA.