Even though this is a global network, involving people of different cultures and acceptable definitions of work behavior, I think the majority of individuals here feel that "groping" is unacceptable behavior during work hours. In America, the legal implications are serious and many businesses have a zero tolerance for sexual harassment. The guy would be hard pressed to argue "she asked it" if she was only 'flirting'.
The best response to a flirtatious co-worker would be "how about joining me for a drink after work" and go from there...IF you are interested. If not, a polite smile and "I need to get back to work now" will cool her off. (I also like the 'fuck off' comment, too!) LOL
But GROPING...at WORK?? Nah...nope..nada...never!