I've been wondering about the name of this technique for years, and finally stumbled upon it. A crash cymbal choke.
https://www.youtube.com/watch?v=duKxQ5VHyyE
 
I am a huge Queen fan and their drummer (Roger Taylor) uses this technique all the time -- as several bands do.
 
How do you do the crash cymbal choke in SI-Drums or Session Drummer? Just wondering if anyone knows any clever techniques to simulate this. Thanks in advance! :)

I can't imagine how to make a VST choke a cymbal but there are lots of audio samples here you could place on the timeline where needed http://www.freesound.org/people/waveydaved/downloaded_sounds/?page=4

When that was not working out of the box with my e-drum, the only idea I have found was:
http://forum.cakewalk.com/How-do-I-create-a-CYMBAL-CHOKE-effect-with-synth-drum-MIDI-m2217742-p2.aspx
 
But more advanced VSTs (like AD) natively support it.
 

Not sure about SI Drums or Session drummer, but with BFD (and I'm pretty sure all the other Drum prog's I have) it's just there, if you are using the PRV or Drum Pane, it's just like selecting a note/a hit and you just place the particular cymbals choke after the cymbals articulation you choose and bob's your uncle. I only use BFD these days, but like I said I'm pretty sure all the others I have have a similar function, can't imagine why they wouldn't, it's a very useful and often used thing.

The choke should be just another note somewhere on keyboard.
Once you find the choke note you can either use that or change it to a note of your choice. Midi mapping

Superior Drummer uses aftertouch to create a cymbal choke.  The advantage over a choked sample is that you can put the choke where you want it.
 

Yes, in a lot of the drum sample programs, there exists samples of the choked cymbal.... and if you set it up correctly, it will stop the normal cymbal hit when you trigger the choke sample (like how each high hat sample cuts off the previous one). Each cymbal sample has many articulations, including a choked articulation in the better sample sets.
 
Without the samples, I am afraid that there is no way to simulate this with MIDI commands.