You mean like a time for "two for one", or other discounts? Not that I know of, although ships usually have a "drink of the day", which may be at a discounted price.
If you happen to be Elite level on Celebrity, they do have a time set aside each day (usually 4 - 6 p. m.) when you can get complimentary cocktails. It will be in Michael's Club, unless there are a large number of Elite folks on board, and in that case, they will open an auxillary lounge. Only Elite members can get the free drinks (although the people in the large suites probably get the same perk).