When you have a crush on somebody whom you would not normally go for. You become nervous while talking to them, or sometimes even just talking about them. The crush is a type of crush for all ages but when you have a
nerd crush it is like you are in middle
school again.
Not meaning you have a crush on a
nerd but that YOU are a nerd because you get nervous when you talk to them, start sweating profusely, etc.