I’m very busy during the week, but at weekends I go out with my colleges.
This was something I overheard someone say, although I sometimes see the same error in writing. Mostly it’s a pronunciation problem that influences written form.
There’s a world of difference between colleges and colleagues:
Whoever you are, and wherever you are, you’re extremely unlikely to go out with your colleges! What you mean is:
But even here there’s a problem. English native speakers are unlikely to refer to the people they study with as colleagues. If the context is education, then a native speaker is more likely to use the following:
If you go out with colleagues, you are going out with the people you work with, and not the people you study with! If you are hanging out with college colleagues then you are probably a teacher or professor hanging out with fellow teachers or professors!