I headbutt my mate. (think of simba and nala of TLK, happy headbutt, lol)
He's usually pretty accepting of it, but sometimes it can hurt a little. ><
We both rawr and mrawr at each other, and snuggling it's impossible NOT to let our a murr or purr.
People watching our affections would think we're psycho, lol.
I also do the same behaviours with my 'pet' cats (I hate that term. -_-;; )
I do massive head tilt when I don't understand something (or find it deeply interesting), plus I do make some sounds, growls, murmurs, like cats do. I don't do it purposefully, I just do it. *blush*