You bump into someone you know, “Hey, what’s up?” Or you might even be a bit alternative and say, “What’s going down?” and do a little hip-hop fingering pointing down action with your elbows up in the air. But here’s the new way to greet someone…
“What’s diagonal?”
It gives the idea of what’s up, but it’s slightly askew. It’s asking about the imperfect what’s up.