I love this challenge.
I noticed yesterday that I hadnt completed it yet since i prefer semtex over frags. But I decided to go for it in ffa on hardhat.
I completed the challenge quickly ...... but I couldnt stop there. It wound up being about the only thing I did the whole match. I was laughing so hard I was about to fall out of my chair.
The odd thing about it though is that I have trouble knifing. But I wasnt having hardly any trouble running up behind people holding a grenade.
My k/d was pretty bad for the match. I think I went like 12/20+ but it was the most fun I've had in a while.