Have fun storming the castle is a popular quote from The Princess Bride, used synonymously with the phrase “good luck with that” in response to impossible attempts.
The phrase became popular due to its comic ambivalence; telling someone to have fun during a gruesome and bloody task such as storming a castle is ridiculous in the least.
The phrase originates from the 1987 movie, The Princess Bride, uttered by Miracle Max (played by Billy Crystal) as the protagonist and his companions rush off to storm a castle.
Fans of the movie immediately adopted the phrase in the years following its release, due to its comic nature.
“Have fun storming the castle” remains a memorable quote to utter whenever someone attempts something straining.
An Urban Dictionary entry was added on the phrase in 2009.