beat off

verb4

1. •
   To drive something away with blows or military force.

   • ...which Action did not so much grieve the English, as trouble and vex the Picts and Scots, who were incessantly gauled and frequently beat off by these Danish Troops. — 1697
2. •
   (informal, vulgar) To masturbate by stimulating one's own penis.

   • Example 1: "I don't need a girlfriend. I just need some swimsuit catalogs, so I can beat off six or seven times a day." — 2003
3. •
   (informal, vulgar) To waste time.

   • I beat off at work all day; I didn't get anything done.
4. •
   (slang) To shoot (a gun).

   • He beat his pistol off into the air.