A person who gets
flustered easily, so much so that a single flirt or romantic/sexual indication might as well make them scream into a pillow, kick their feet non-stop, blush
intensely, and have many other over-the-top reactions related to being
flustered.
A: Hey, is
your boyfriend alright? He's been red as a tomato all morning!
B: Oh yeah, I told him I would give him kisses till he's breathless,
that's why.
A: I see... He's a flusterfuck, alright.
B:
Definitely.