SLIP' (4 letters) The term LEAK GIVEAWAY can be summarized by two crossword solutions: HISS and SLIP. HISS is a sound made by a snake or other reptile, and is also used to describe a sound made when air or gas escapes from a small opening. SLIP is an action of sliding or slipping on a surface, and can also refer to an unintentional mistake or error. Together, these two words can be used to describe the act of something being unintentionally revealed or given away.