Some catch

"Some catch" means that that person is very good looking and would be a great girlfriend/boyfriend.

That girl Sophie is some catch

catch some z's

to sleep (the zzz in the word bubble over sleepers heads in comics).

I'm going to catch some z's before I go to work.

catch some rays

to lie or sit outside in the sun

I thought I'd take my lunch outside and catch some rays.

Catch some fish

Gender neutral way of saying that you will be having sex.
Akin to getting some pussy/dick.

"Hey, is Tom coming to the party on Friday?"
"Nah, he had a real nice date last night and is hoping to catch some fish on Friday."

Catch some Zs

(idiom) Go to sleep

Aa Bb Cc

catch some zeds

Simply means, just trying to get some sleep.

Damn...I haven't slept for 36 hours, I'm going to try to catch some zeds.

catch some smoke

A person who says this usually wants to square up or fight.

Man 1: You trying to catch some smoke?
Man 2: No smoke please.