Q:

"slap yourself five"

Any ideas about what the "slap yourself five" means in the following context?

"When someone says something you disagree with, before you call that person names and slap yourself five for your brilliant rebuttal, take a second to consider it fairly on its own terms."

A:

To "give someone five" is to slap hands together in a congratulatory gesture. 
Most often it is heard in the context of "gimme five" or "high five" (the act of slapping the palms together over the heads of the two participants). In this case, to "slap yourself five" would mean to congratulate yourself. Cf. "give yourself a pat on the back."
Edit:
See also: "Give me five" and "slap me five": any difference?

