My wife works for big tech, a company that is quite well known. Off of a ship, 9 times out of 10 when she identifies her employer the first questions is "Do you have a stickers?". What we have figured out is that when we tip on a ship, we will always add a sticker for the server (along with a small cash gratuity). Most of the time the recipient will recognize what it is and seems to be grateful. Yes, over a sticker, I still shake my head at this. This practice works well on Non 6 star or all included ships, not yet sure how we will handle tipping on the Voyager in April, but vast quantities of stickers have already been ordered. I have never been accused of being ordinary!