One of my colleagues, happens to be in a fortunate situation to control English almost as a mother tounge. It is always a pleasure to get fresh new ideas from him.
Lately he pops up again and again the under-deliver-over-promise saying.
In Eastern Europe this is one thing most people do not seem to value enough.
Though at some level there can be a trap in this I think that applied carefully and right this can serve as a key element of scrum.
Yeah, I know -- Scrum is about honesty, but currently I seem so many bad examples of over-promising and under-delivering that as a direction is seems to be very tempting.
Keeping the team honest should be the most essential part of any working methodology & project...