the streets, “crab potting” (or “crabs in a bucket”) describes a toxic, jealous mentality within a group. It means dragging down anyone who tries to succeed, quit the neighborhood, or do better, operating under the spiteful philosophy: “If I can’t have it, neither can you”. [1, 2, 3]

The metaphor comes from how crabs behave in a bucket. While a single crab can easily climb out and escape, multiple crabs trapped together will actively pull down any peer that tries to crawl out, ensuring none of them ever get free. [1, 2]

In a sentence:

• “I finally got that job offer, but the guys downtown started crab potting and saying I was selling out.”

You can learn more about this behavior and its psychology on the Wikipedia Crab Mentality page. [1]