Spoil a surprise is an expression used to describe the act of ruining a surprise for someone. This can be done by either peeking at the surprise or telling someone about it. The crossword solutions for this term are PEEK (4 letters) and TELL (4 letters). PEEK is an action that involves looking at something before it is revealed, while TELL is an action that involves sharing information with someone else. Both of these actions can be used to spoil a surprise.