The phrase "What the fuck are you doing" aka "What on fucking earth are you doing" is commonly used by the teenage population. You would use one or BOTH of these phrases if you see someone.. say.... washing their car in 20 degree weather. In this case you would have to make some modifications such as....
What the fuck are you doing!? Do you fucking love hypothermia?
Uttered when a vessel (usually sea-based) makes a wrong turn; accidentally uttered by Sue Simmons of WNBC-4 NY when she unexpectedly saw a cruise liner turn at an awkward angle.
"At eleven, paying more at the grocer, but getting less. We'll tell you how to get the most... what the fuck are you doing ?!"
Favorite catch phrase of WNBC's Sue Simmons, first debuted May 12, 2008 and later seen on David Letterman.