Choose the best phrase to give life-saving advice to a friend with terrible ideas.

If I ___ you, I wouldn't try to steal a sandwich from that angry goose.

The correct answer is were.

When giving advice using a hypothetical scenario, we use the phrase "If I were you." This uses the subjunctive mood, where "were" is the correct form for all subjects (even "I" or "he/she/it") to show that the situation is contrary to fact.