it means to Follow Up
Online jargon, also known as text messageshorthand, used in texting, online chat, instantmessaging, email, blogs, and newsgrouppostings. These types of abbreviations are also referred to as chatacronyms.For the largest list of Internet acronyms and text message jargon, click on "more info" below!
Special thanks to Cristina Keleshian for recommending this one!
NetLingo Classification: Acronyms and Text Message