Good night
Methods of griefing differ from game to game. What might be considered griefing in one area of a game may even be an intended function or mechanic in another area. Common methods may include but are not limited to:

Intentional friendly fire or deliberately performing actions detrimental to other team members' game performance.
Wasting or destroying key game elements
Colluding with opponents
Giving false information
Faking extreme incompetence with the intent of hurting teammates or failing an in-game objective
Deliberately blocking shots from a player's own team, or blocking a player's view by standing in front of them so they cannot damage the enemy[5]
Trapping teammates in inescapable locations by using physics props, special abilities, or teleportation
Actions undertaken to waste other players' time.
Playing as slowly as possible
Hiding from an enemy when there is no tactical benefit in doing so
If a game interface element has no time limit, leaving their computer (going "AFK"), potentially forcing the other players to leave the game (which may incur a penalty for leaving)
Constantly pausing the game or lowering its speed as much as possible, in the hopes that their target quit in frustration
Causing a player disproportionate loss or reversing their progress.
Destroying or modifying other players' creations in sandbox games like Minecraft and Terraria
Driving vehicles backwards around lapped courses in multiplayer racing games, often done with the intent of crashing head-on into whoever is in first place
Using exploits (taking advantage of bugs in a game).
Illegally exiting a map's boundaries to gain a strategic advantage
In a co-op or multiplayer game, destroying or otherwise denying access to items without which other players cannot finish the game
Purposeful violation of server rules or guidelines.
Impersonation of administrators or other players through similar screen names
Written or verbal insults, including false accusations of cheating or griefing