I have the Tunnocks jersey, I love it. The other day I was highly amused to realise that when wearing it, I have "Scotland's finest!" written right across my bum. I pointed this out to my husband, who in return indicated that I had "Tea Cakes" written right across my boobs...
As well as the Tunnocks jersey, I have the Marmite Hate Jams one...and I'm looking for the Irn-Bru one next, to be bought as a 'commuting milestone celebration'.
Before I cycle-commuted, I could only identify two of the cyclists I regularly passed on my way to work - one because he always carries his stuff in a carrier bag in his left hand, the other because he usually has four Sainsbury's bags of shopping when he goes home late one day a week!! As a cyclist I now identify a few more regulars when I am driving.
However (and I am getting to the point here), despite being a far-from-regular commuter, I was in a shop, not wearing cycling gear, and was asked if I was "the Marmite lady" who cycles along that road. I think that's part of the idea of the more unusual shirt, you make yourself distinct and that somehow personalises you to those who see you regularly.
I like the
Northwave Heart jersey - it helps that I work in a Cardiovascular department, I suppose

I ought to hunt one down in a suitable size before everyone is sold out...