Literal: when the male does a complete, thorough, properly executed, turkey slap (a complete full swing of his penis across the face of another, often a female).

Metaphorical: to have a complete win through destruction of the opposing side via going all in and risking everything.
Example 1: Cindy was giving Jordyn the smack, so Jordyn gave Cindy The Full Swing.

Example 2: Whilst doing the cannon rush in Starcraft 2, let’s go for The Full Swing.
by Starcraft 2 World Champion January 9, 2019
at the climax, or busiest time, of an event.
The party was in full swing.
by tom_od May 14, 2010