The term "tf" is often used as an abbreviation for "the fuck," which is a colloquial expression used to convey surprise, confusion, or disbelief. It's usually employed in informal or slang contexts, especially in digital communication like texting or on social media platforms.
The expression "the fuck" has its origins in the Old English word "fūckan," which means "to strike" or "to penetrate." Over time, it evolved into various forms and became a vulgar term used for sexual intercourse. Its usage as an expression of disbelief or surprise has become common in modern vernacular, especially among younger generations.