Rabbit hearted
The feeling evoked from immense love that can only hope to be somewhat accurately described as one's heart beating so incredibly fast that it is like a hastily bustling rabbit; sometimes accompanied by wide smiles and feelings of warmth.
"When Kyle Edward gazes upon Samantha Marie's face and stares into those fathomless pools of sapphire that are her eyes he instantly becomes rabbit hearted."
rabbit's heart
An antiquated, schoolyard term denoting the grasping/throttling of male genitals in a rapid, yet even, measure; so to resemble the beating heart of a rabbit. Believed to have originated in the late 1980's or early 1990's, and may in fact be regional to the greater northeast, though this is admittedly speculative.
James: "Hey dude, you ever see a rabbit's heart?"
Mike: (pukes)
Mike: (pukes)