Como dizer "Coçar o saco" em inglês

Eu diria

I was hanging around.

Chill out: ficar de bobeira

- I'm just chilling out.

Minhas sugestões:

Loose end: I'm at a loose end.
Laze around: I'm lazing around!

Tim,

It makes perfect sense! It has everything to do with "coçando o saco".

Goof off = avoid doing any work due to laziness
He was fired because he used to good off a lot .
He was fired due to his goof- offs.

The way the initial sentence was put it could be "I am (just) sitting around and with nothing to do." (my day off, it's a rainy day and I am financially broken).
If you are retired somebody else may think you are at home with 'all that extra time', it's the first step to ask you to do favors and errands for free, sometimes it can be a case of 'taking advantage' of the situation.

Minhas sugestões:

Twiddling one's thumbs
- I was just sitting there, twiddling my thumbs, waiting for something...any thing to happen.

Sitting on one's bum (chulo)
Bum = backside
Sitting on one's backside.

- Stop sitting on your bum doing nothing. Come and help!

Hello, are you asking about how can you say "coçar o saco" in English?
That is an English slang: I have a friend who lived in the USA for a long time and she told me exactly that: scratching balls.

- What are you doing right now?
- I am scratching my balls.
- Means that I am not doing anything.
- I hope I've taken off your doubt.

Uma amiga texana usou essa frase aí "I'm just chilling out" pra dizer que estava tarde da noite jogando conversa fora com uma amiga.