From Rap Dictionary
- To show one's mettle, flexing one's muscles, showing one's arsenal and readiness to put it to use, letting one's pugilistic prowess be known. To strike someone, or to get up in someones face for intimidation. "I use my nine when suckas start to flex" -- Ice Cube (Man's best friend ).
- Scratching, from flexing of the wrist. Rakim used to talk about Eric B being on the flex.
- To have sexual intercourse.
- In some cases, refers to one's departure. "Imma flex, yo". See also Bounce.
- To sell fake crack.
- To tell a lie. "Man, quit flexin`" -Flexer - liar
- Alright. In Dutch (Hip Hop) slang, when someone asks you: "Alles flex?" it means: "How are you doing?" And when you answer: "Alles flex!" it means: "I'm doing alright" Who the fuck listens to dutch Hip Hop?