Tits or GTFO is a foundational piece of internet slang that emerged from the /b/ board of 4chan around 2004. It was famously categorized as Rule 31 of the internet, stating that any user claiming to be female must provide photographic proof of their gender or leave the conversation. Over time, the phrase transcended its original roots to become a generalized, often ironic way of telling someone to stop seeking attention or to provide evidence for their claims. Today, it stands as a relic of the 'wild west' era of the internet, frequently used as a nostalgic reference to early message board culture and anonymous social dynamics.