Since English doesn't have codified politeness levels in grammatical structures (like Japanese does with eg verb endings, where tabe-ru is less polite than tabe-masu for the same verb meaning "eat"), we tend to make requests longer the more polite we're being.
For example:
- Bring me that.
- Hey/Yo, bring me that.
- Can you bring me that?
- Could you bring me that?
- Would you mind bringing me that?
- When you get a chance could you bring me that?
- If if fits into your schedule I'd appreciate it if you could bring me that.
- I know you're really busy but it would really help me out a lot if you could bring me that.
With close friends the first one is ok(ish) if your tone isn't too commanding, but I'd normally stick to 2 through 4 (or 5). For some reason a "please" sounds overly polite whereas a "thanks" upon receiving the request doesn't. I imagine this is different for other regions. I'm from the US northeast, but people from the south probably feel differently.
