A level above mere "screwing the pooch" – i.e., the act of screwing up so badly and losing that it compares to former White House Communications Director Anthony "Mooch" Scaramucci's irreparable (possibly tragic) mistakes felt on a global scale.
You really did "screw the mooch" for all of us when you lost our biggest account and called the client's wife a huge slut. You know how hard it was to get that business with the Saudi Arabin king?!
3. To waste time. Usually connected to people not working to their potential.
"Bob really screwed the pooch on that assignment. Not a single stat was correct"
"Jen loves to screw the pooch. She has a world record high score in tetris on her office computer."
.... You know how (in the California highway construction) one guy actually works, while 3 guys stand around holding shovels watching him? - Those guys went to Screw the Pooch college to learn how to do that.
Screw The Crew is when someone (usually a dirty old man) is in the situation of finding someone hot (or not) at work and inevitably drawn into having sex with them (usually with consent). This is often made worse by those in positions of power eg. 17 year old McDonalds night-shift manager who hits on the barely-legals working underneath them (sometimes literally working underneath them).
"You've heard of not shitting in your own nest? Well, my job-retaining policy is to not screw the crew."
"Oh Geoff, yeah, he definitely screws the crew. Saw him leaning up against that new girl the other day showing her his little French Fry. She was just as bad...all over him like hot mayonnaise...and just as rancid."