Don't Bite the Fishing Pole
White to move. Don't take it: hit the center.
Snort's knight on g4 is the bait. Ignore it and play in the center.
Hint
The g4 knight is bait. Take the center instead.
Answer
d4 — Correct! d4 ignores the bait and White is better.
The tempting mistake
Taking the knight is the bite: the h-column opens and his queen mates on h2.
The idea
A piece offered next to your castled king is often a hook. Take the center instead.
This defense is one of 30 quick puzzles in the Chess in 40 Seconds trainer: find the move on the board, get a hint if you're stuck, and learn the idea so you never fall for it in your own games.