According to TMZ he claimed to be the king, accepted a bet, but has yet to pay up.
Get on! RT @Millwall I bet you your jersey you can't beat me, a golden fox and one of the best players in the world pic.twitter.com/XliiU2Sa44
— Arian Foster (@ArianFoster) May 2, 2014
The two have played a few times now--and Foster has yet to win. Martyn says Foster continues to challenge him, but has yet to pay up.
I'm going to guess that Foster just hasn't gotten to it yet. We are talking about a guy that sought out a person that thought she had taken a picture with him but had been tricked so that she could actually get a pic with him.
That doesn't sound like someone that is going to sweat a giving a fan a jersey over a Twitter bet.