Do some companions actually respond, with irritation, to multiclicking? That was my favorite part of Blizzard games for a long time - harassing Jim Raynor and Arthas and so on with a zillion clicks - but I long ago stopped trying it in BioWare games.
They do. 4X's is particularly funny. "Don't worry, sir, my armored exterior is completely impervious to your touch, no matter how persistant!"
Back on the subject of Fun Companions, I would also like to nominate Corso. For Male Smugglers he's quite funny, and you actually gain affection with him by hitting on every woman in sight. I found that bit hilarious.
Also, Mako and Gault are both very fun to be around. Especially Gault. Definitely Gault.