The phrase "start swimming" is a phrase used by teens to tell someone to fight. Start swimming is a nice and fun way to tell someone to fight.
You wanna talk shit? Hoe start swimming!
Your either with us, or you are on your own.
Person A: "Brenda really doesn't like the new rules"
Person B "Then she needs to start rowing or start swimming"
Get with it or get out.
Person A: "I don't like these new rules"
Person B: " Well start rowing or start swimming."