get back at
Take revenge on, as in Watch out for Peter; he's sure to get back at you. Similarly, get one's own back means simply “get revenge,” as in She finally saw a chance to get her own back. The first expression dates from the late 1800s, the second from the early 1900s.
Words nearby get back at
get around,
get at,
get away,
get away with,
get back,
get back at,
get back to,
get behind,
get better,
get busy,
get by