How do you take a screenshot of a snapchat on a Samsung Galaxy S2 (T-mobile)?

[Alexmilr01]

I normally screenshot using the home button and power button at the same time, but that won't work for snapchat because I have to have my finger pressed on the screen to hold down the picture. Any other methods that you have tried that have worked?
I also want to add that I don't want to jailbreak my phone, so if thats the only other option, I guess I can live without being able to screenshot:/

 

[NeAeLeTeChristian]

On my galaxy nexus, you press the volume down button and the power button together. I think that works on any android phone.