It's mostly delighted or pleased, although it can occasionally mean the opposite, especially in the military. I believe it started off as "proud." This bunny is delighted and proud of his new rug.

I'm amazed he knows how to use a litterbox and not just poop everywhere. That's probably how he earned his nice rug!

Chuffed is slang for very pleased in the UK. More specifically it's when something good has just happened to you that's causing you to grin uncontrollably like a lunatic.

As my crude father would say: "I'm chuffed to buggery!"

Although buggery is a bad thing on its own, when combined with chuffed it's like a +1 enchantment instead.

It's the most negative-sounding positive word, isn't it?

Satisfied. Smug but not in a negative way.

Especially when someone gets "chuffed to bits"

Pleased

I have the same reaction to nonplussed

Up the chuff = good, down the chuff = bad

"Chuff" in the context of rock climbing = bad, made an effort but didn't get very far / fell a lot

So you're chuffed about it?