What does the expression red hot tip mean?
It can mean several things, depending on whether it is meant
literally or as an idiom. Literally, it would mean that the tip of
something is red-hot, or glowing with heat. As an idiom, a "tip" is
information that can be used in a situation, so a "red-hot" one
would be something that is especially important at the moment,
something timely and greatly useful.