He is challenging you to try and do this so you realize how hard it really is and that all that is happening is the other player is getting lucky.
Personally, though I do play Hardcore quite alot, I've not personally been killed this way nor have I witnessed this. However, someone with a modded controller, such as Aim Assissted or what not could have done this.
I frequently play with a sniper and have never got a hipfire shot longer than a couple of feet even before the patch it was pretty hard so if someone manages to hipfire you from a decent distance you should bow down and kiss their feet as I would love to see you attempt and fail this in my experience the only people who i've known to moan about snipers are those who can't quickscope once they know how to they love it.
I have diamond camo for my snipers and I probably only got 2 hip fire kills out of all the time that i've used them.
Do you realize how often hipfire kills actually happen with snipers? Try yourself, then come back.
I don't really have problems with people hipfiring me with a sniper.
I'd say just be glad the barret isn't in this game (ate least in multiplayer)
If you fired that thing fast enough you'd always get enough hipfire kills.
Saw a funny video of someone getting a multikill spraying the barret in the camping room in Seatown in YouTube, think it was called something like 'the best shotgun in mw3'. I had loads of double / triples hip fire trolling with the RSASS. I miss MW3.
I do really miss the barret though. greatest sniper rifle ever in CoD
I've had some very accurate (lucky) sniper no scopes (hip fires) as part of my silly FFA final killcams crusade, I'd say I get a OHK about 60% of the time.