Idiom: be my guest
Matt: Hey man, I’m going to San Diego next year.
Dee: Oh really? Can I come too?
Matt: Be my guest.
Dee: Really? That’s awesome.
Thomas: Do you think I can turn in those reports on Monday of next week?
Charles: Be my guest. They’re not due until Tuesday anyway.
Meaning: "Be my guest" means: “go ahead,” “help yourself,” or it could mean giving someone permission to do something. It’s a neutral term used by many people in formal or informal settings.