What does YTF mean in texting?

I'm curious to know, could you please clarify for me what the acronym "YTF" stands for when it's used in text messaging? It seems to be a common abbreviation that I've come across a few times but I'm still unsure of its exact meaning. Is it a slang term that's widely used among certain groups of people, or is it perhaps a shortened version of a longer phrase? Any insight you could provide would be greatly appreciated.