1. An internet meme that is based around a gameplay element in the popular online sandbox/adventure game Minecraft where your character can punch trees to break them and collect their wood. This is a source of TV shirts and other internet jokes.

2. It can also be used perversively (like a That's What She Said joke).
3. It can also be used to say you're going to play Minecraft

Examples:
1. Dude1: Why are you punching that tree
Dude2: They give me wood when I do this
Dude1: Bro that's only in Minecraft
2. Punching trees gives me a hard-on.
3. Dude1: Hey, I'm going to go punch some trees
Dude2: Talking about Minecraft?
Dude1: No... I'm just really mad right now.