Como dizer "Oi, sumido(a)!" em inglês.

When someone says Hi, stranger! to you, he / she isn't really calling you a stranger.
It is just a funny way of saying something like:

1. Hi, I haven't seen you in while.
- E aí? Faz um tempo que não vejo você(s).

2. If I'm not mistaken, we've met before.
- Se não estou enganado(a), já nos encontramos.

3. I know you, but you’ve been out of touch. (maybe).
- Eu conheço você(s), mas você(s) está(-ão) sumido(a)(-s).
- Eu te conheço, mas faz certo tempo que não te vejo.
- Eu te conheço, mas já tem um tempo que não trocamos uma ideia.

Every time you see a friend or anyone else you’re close to after a period of absence you can say Hello, stranger!. Nowadays, it is also a common greeting on social networks.

Some people are lousy at keeping in touch, and we are perflectly aware of that. Sometimes we need to ask them to not be a stranger!, in other words, to give us a call or come by for a visit some time.

If you consider yourself an annoying person, do not expect so much of them! Okay?

Some people enjoy more friendly environments than others.
Some are very busy too meet up and others just prefer to be at lonely places.

Try to be more friendly as much as you can.

Comprehension is the key to make friends forever.

ENGLISH VOCABULARY	PORTUGUESE TERM
Hi, stranger!	Oi, sumido(a)! / desaparecido(a)! (Informal)
Don't be a stranger!	Vê se aparece! / Não some! (Informal)
I am lousy at keeping in touch.	Eu sou ruim em manter contatos.

I hope you appreciate it!
Enjoy your studies!