What's your best unconventional "blessing" like when people tell an actor "break a leg!"
In inpatient psychiatry I tell my coworkers "I hope your shift is mind-numbingly boring" or something similar (keyword being boring) because in my line of work, interesting (usually) = bad.
"Merde". As in, the french word for "shit" - or, should we say, "horseshit". Why? Well because at the time of horse-drawn carriages, a successful play at the theatre would leave a lot of horseshit in front if the theatre from the many, many coaches awaiting their fares.