To Fluttershy's brain, buzzy was that feeling of warm fuzzies that kept radiating through her whenever Carmen was in close proximity. She had no idea as of yet - though she was now starting to become very aware - that the buzzy was a sign of attraction. She just knew that she liked it. It was warm, and comfortable, with a bit of energy like lightning.
That didn't really change when Carmen pressed her lips against hers, either, and instead of feeling like a low-pitched scream was going off in her head, she felt like bouncing on the rooftops and flying through the air. The buzziness hadn't disappeared either, but was instead rippling through her with greater ferocity, colliding with the butterflies in her stomach and pretty much overwriting them entirely.
After a few seconds she even realised she wanted to kiss back, and though she wasn't sure she was doing it right, she certainly gave it an effort.