やっちゃった

やっちゃった is a casual contraction of やってしまった (did and regret it). The 〜ちゃった / 〜じゃった pattern is the casual spoken form of 〜てしまった, which expresses an action done completely, often with a sense of regret.

Forms

やってしまった → やっちゃった

Register

やっちゃった is lighter than やらかした. It suits minor slip-ups and has a self-deprecating, sometimes cute quality:

• やっちゃった: "oops" — minor mistake, somewhat playful
• やらかした: "I screwed up" — bigger blunder, more serious

Common patterns

This contraction is widely used beyond やる:

• 食(た)べちゃった: I ate it (and maybe shouldn't have)
• 忘(わす)れちゃった: I forgot (oops)
• 壊(こわ)しちゃった: I broke it (accidentally)
• 言(い)っちゃった: I said it (slipped out)

The pattern usually implies the action happened unintentionally or against the speaker's better judgment, though it can also just emphasize that an action was completed, with no regret intended.