You were probably told on day one of jiu-jitsu class that you shouldn't try and attack people from inside the closed guard.

Why? 

Because the guy on bottom has wayyyyy more chance of tapping you out before you could make him submit. 

Thing is, that's not to say it's not impossible. They say that in jiu-jitsu there are guidelines but not rules. A no-no for somebody might be bread-and-butter for somebody else. 

Case in point: the Ezekiel choke (sleeve choke) from inside the closed guard. 

Yes, this move can and does work. BUT it is hard to pull off and even more so against a renowned closed guard wizard like Jaime Canuto of GF Team.

Still, it didn't stop Sebastien Brosche, that crazy yoga hippy from Scandinavia who has made a career of making weird shit work in competition. Brosche (he's officially known as Andreas but nobody calls him that) has a whole repertoire of nasty techniques that blur the line of legal/illegal and acceptable/unadvised.

So, as we see below, this is what happens when you try to choke somebody from inside their closed guard.