Touché is used as an acknowledgment during a discussion of a good or clever point, usually after contradicting the user's previous point.
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.
1) Peter: I'm pretty sure we've never had a volcano either.
Salesman: Well don't you think we're overdue for one?
Peter: Touché salesman.
1. A phrase used to concede a point, typically one of no-contest, such as pointing out an obvious correction.
This term is not to be confused with either the words touché or salesman.
2. a common reference to Family Guy
"Hold on there, son. 2+2=4, not 5."