slap in the face

Short definition from Wiktionary

Noun

1. 1
   Something unexpectedly said or done which causes shock or offense; an insult, rebuke, or rebuff.
2. 2
   Used other than figuratively or idiomatically: see slap, in, the, face. (This sense is a translation hub.)

Verb

1. 1
   To insult or offend unnecessarily.
2. 2
   To be or suddenly become bluntly obvious to.