Adding 'salesman' to the end provides emphasis and a bit of humor, first used by Peter Griffin in Family Guy. Although Peter was actually speaking to a salesman, one doesn't necessarily need to be speaking to a salesman for this phrase to be used.
Salesman: Well don't you think we're overdue for one?
Peter: Touché salesman.
This term is not to be confused with either the words touché or salesman.
2. a common reference to Family Guy