Have to agree with Sally, it's not pleasant being butted up the arse or on the leg by a ram lamb that is too friendly. It's no problem with ewe lambs or wethers, but being too friendly with anything with male hormones is asking for trouble. I'd never ever hand feed any ram or ram lamb either, for the same reason, you don't want them to associate your hand with food.
I have one ram lamb myself who has started to get a little too friendly (not my doing, I've never had any interaction with him ever!). So every time he comes near me now to try to make him run away, either by just rushing towards him, or if he's really close, I give him a shove on the shoulder (like his mum would).