Don't do that. It just pisses them off even more.
No, it's not. Are you people really so desperate for antagonism and drama that you're now seeing enemies where they don't exist?
Rofl, no need to be a hypocrit.
And yes, you should do a sleight-free trick or a trick with a force or something very small they will never catch. This doesn't make the heckler angry it just puts him in his place. You can also say that your not going to perform if this heckler, or hecklers continue to heckle. I've had groups of people push those people or tell those hecklers to go away, it's very funny. Then again, they might like the heckler and dislike you for not continuing the trick, but you never want to perform for a crowd that is wanting to see you screw up, might as well just not even or or accept a trick.
Also, if they want to shuffle the deck, it means they think you did something funny. However there's always people who will try to be difficult.
You could glimpse the chosen card and do a mind-reading demonstration or test there "poker face" whatever you want.
If the heckler comes up to you and asks for a trick just say ," I don't have my cards/coins/ropes/ sponge balls today, sorry" or something. I highly doubt they will go out of their way to frisk you for your magic material.
Hope this helps
P.S: Thank you for giving such wonderful advice to our friend here Steerpike.