Wingman

In a social situation, a guy's 'wingman' is another guy who acts at the backup for the 'lead man' as he tries to pick up women. The wingman often intercepts the 'target' woman's less-desirable friend and keeps her busy. [1]

At Penny's Halloween party, Leonard expected Sheldon to act as his wingman, which in this case meant that Leonard wouldn't have to go talk to Penny and Kurt alone. Sheldon pointed out that "...if we're going to use flight metaphors, I'm much more suited to being the guy from the FAA analysing wreckage."

As the confrontation with Kurt at the party becomes increasingly hostile, Sheldon reminds Leonard in an aside that "...while my moral support is absolute, in a physical confrontation I will be less than useless."(0106)

Howard studies various "techniques" for picking up women and uses the term "wingman" when he invites the other guys to come with him to bars (0208).