My very first belly rub from someone other than my DF or my mum came from of all people our lunch truck lady at work. I almost died. It was so unexpected. I must have shown my shock as she's never done it again. That was a couple of months ago.

My DF does it all the time (of course). My mum does it when greeting me each time I see her (whilst asking how "our baby" is going..... she's been waiting 14 years for this). My MIL's fiance does it every now and then, he's always been one to give me a hug for no particular reason (and I don't mind). My MIL only does it if prompted to by her son (wish he wouldn't, I'd just rather it happen naturally, not from a prompt).