In this achievement all you need to do is get in the mission, flush the toilet 1 time and get out of the mission, it still counts.
Bad Call - 1
Trial by Blood - 2
Toxic Love - 2
Short Circuit - 1 - As you get in the bathroom a ghost will flush it, wait a moment to do it.
Italian Job - 2
Affair With Death - 2
Friendly Fire - 1
Party's Over - 3
Modern Art - 6
Call In Dead - 4