I'd rather they rip the bandaid off and not pretend they are my friend. You are firing me. You are removing me from my source of income. Stop trying to be "pleasant" because it just looks like you are enjoying it.
No smiles, no affected happiness, no weasel words about being "let go". Just say "yeah, sorry, you're fired". The more emotionless you can make it on your end, the better.
Heck don't even fire me in person. Send me an e-mail. It's a lot more... Humane. Less cruel.