Anthony Flex circulates online as a user-shared soundboard and short-form video clip, where its meaning comes from usage rather than a single known source. Creators reuse the name as a quick label for a flex, attaching it to gym footage, character edits, sports moments and comedy posts where someone is showing off. Its short length makes it easy to loop, layer over transitions and share as an MP3. It stays popular because the flex joke is instantly understood across platforms, even without knowing the original context of the recording.