My pledge nickname is B.A.V., which sucks, because the other girls have such great names like Blue Balls and Cherrypicker.
Pretty much all my friends call me Kath, a lot of girls in the house call me K-Dawg, and I also get #2 a lot due to our evil numbering system.
However, my favorite nickname of all time would be the names we gave each other in high school CC - I'm Fatty McChubbs, another girl was Fatty T, then we had Saddlebags, Cellulite, Cottage Cheese, etc...