This most often happens when the copper washer is left out after a drain and oil change. Couple of things you can try, but they can be risky.
#1 drill the center of the plug and try an Easy Out.
#2 try it with a brand new visegrip after appying some heat (read this as a propane torch, not oxyacetylene.
#3 get someone to weld (arc) a foot long piece of bar stock to the end of the drain plug and using the mechanical advantage this offers break it loose.
#4 Try drilling out the whole thing and hope that you don't bugger up the threads too much.

Good Luck...

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Jeff Lawrence
1987 300e
1989 300e
2000 Dodge Grand Caravan SE