Flummoxed
The confused, tongue tied and speachless state a boy falls into when the girl he's crushing on talks to him unexpectedly for the first time.
Example:
Friend: hey, did you finally talk to Heidi?
Boy: no, I saw her at lunch but I got all flummoxed.
Friend 2: I heard you were like a deer in the headlights.
Friend: hey, did you finally talk to Heidi?
Boy: no, I saw her at lunch but I got all flummoxed.
Friend 2: I heard you were like a deer in the headlights.