a happy bunny [USA happy puppy/camper]

Meaning 'contented'. Often negative.
--Are you a happy bunny?
--Ha ha, yes! I am!
A happy bunny, which literally means a happy 'rabbit'. It's another of those strange English expressions. The meaning is that I look happy. Why rabbits are involved I don't know, that's just the way it is. Here are some examples of this expression in use.
Examples:-
--That's brilliant news, you must be a very happy bunny!
--I'm a happy bunny today because I passed my English test.
--Li: Yes, Neil, I am a happy bunny! But what about you? Is something wrong?
--Neil: I'm not a happy bunny. You see … Something awful happened today.
--Li: Oh. Neil is not a happy bunny – said to a person who is unhappy.
--Someone's stolen Michael's car. He is not a happy bunny!
--Jane has not been a happy bunny ever since she broke up with her boyfriend.
The origin is obscure, only that the expression has been in use in the UK since 1991. Maybe it is from the idea of rabbits playing and jumping up & down?! The USA usage is more obvious: puppies are playful and in the US summer camps for teeny-boppers the neophytes are expected to show party & team spirit. :clap::down::down

...
χαρούμενος, χαμογελαστός, περιχαρής, καταχαρούμενος, ολόχαρος (regional) [all of them neutral]
χαρωπός (especially for youthful joy; neutral, but it can be negative)
χαζοχαρούμενος (pejorative)

Χαμογελώ μέχρι τ' αυτιά (grin / smile from ear to ear), χοροπηδώ (bunnywise) / λάμπω / αστράφτω απ' τη χαρά,
ξεχειλίζω από χαρά, πετάω τη σκούφια μου (throw my cap in the air), τρελός από χαρά

For the positive use: είμαι στα πάνω μου

For the negative use: δεν είμαι στα καλύτερά μου / δεν είμαι στις καλύτερές μου

Neil:
Είμ’ ανεβασμένος, στα σύννεφα πετάω...
Είμαι στα χάι μου, όταν σ’ έχω πλάι μου.
Κι όταν είσαι χώρια μου, με τρώει η στεναχώρια μου

Li: Είμαι στα πάνω μου, είμαι στα ωραία μου...

Neil: Μ' έχεις κάνει χάλια...

Trash music is not a privilege, it's a human right.