To feel butterflies in your stomach for someone because of the attraction felt towards that person, or, the feeling you get when anticipating an interaction with someone that you're really attracted to physically.
The term derives from the show "Sex in the City" (Season 5, Episodes 74 & 75).
"Oh, he makes me feel so..... zsa zsa zu!"
"How do you sustain a relationship without the zsa zsa zsu?
The what?
That butterflies-in-your-stomach thing that happens when you not only love the person, but you gotta have them. Isn't that what gets you through the years? Even if it fades, at least you have the memory of the zsa zsa zsu." ~Sex in the City, Season 5, Episode 8

