I don't understand why you would do it. I don't bring food for waiters at restaurants or staff at hotel/airport lounges.

That being said - I once aligned my return with a friend who was serving the same flight, BOM-SIN. He's a fan of Indian sweets and snacks so I bought some stuff during my stay in India for him and the crew to share onboard. When I reached at the galley and asked if he was around 'cause I wanted to give him some snacks and chat, the crew member asked me if I was from management. For reference, this was on SQ.