1) Big finale 2) Bottling device 3) Climactic move 4) Finale 1) Finale 
• (n.) One whose business is to make or sell caps. • (n.) An instrument for applying a percussion cap to a gun or cartridge. • (n.) A by-bidder; a decoy for gamblers [Slang, U. S.].
Meaning as a surname: Cap maker.
Cap'per noun 1. One whose business is to make or sell caps. 2. A by-bidder; a decoy for gamblers. [ Slang, U. S.] 3. An instrument for applying a percussion cap to a gun or cartridge. 
the last topper (see below), geared towards getting the biggest laugh. 
Capper is American slang for a by-bidder; a decoy for gamblers.
an antiquated term for the final in a series of jokes on the same
an antiquated term for the final in a series of jokes on the same subject matter which ends the routine with the biggest laugh.