1. When
something happens that reminds you of an embarrassing,
difficult, or so-disturbing-that-you'll-never-be-able-to-unsee-it event in your life.
2. Actual flashbacks to actual battles. Can happen with PTSD.
Oh my god, that was the same position my
parents used when I walked in on them as a kid. I'm having
war flashbacks!
Don't you
trigger a war flashback, son. I once killed a man!