This is a polite question to ask when you need to get into a place that's being blocked by someone's body. Some other examples of situations that you can use this in are:
- when you're walking through a crowd of people.
- when you need to walk past people sitting in your row to get to your seat in a theater.
"Can I slide past you?" is a friendly way to ask this. It sounds friendly because the word "slide" sounds so smooth and easy. It's like you're saying, "Can I go past you quietly and without bothering you much?"
If you're more annoyed or if you're a loud and aggressive person, you can ask like this:
Can I get by?
You could also ask "May I...?"