I don't have anything egregious from work, but just a compilation of little things my coworkers do that make me shake my head (and also wonder what I'm doing that other people see as crazy).
1) We are reimbursed for mileage when driving personal vehicles between facilities. One of my coworkers drives ~ 5 miles at the end of each workday to do a daily check at a different building. She NEVER requests mileage reimbursement, I'm assuming because it is only like $2.50 a trip. She's literally leaving > $500 tax-free money on the table every year. Five. Hundred. Dollars. For something she already does.
2) Same coworker drinks tea every morning in a new styrofoam cup. Our office gave us all branded coffee mugs for Christmas. She didn't even have to bring a mug in, just use the one they gave us and wash it in the break room.
3) Another coworker has only one credit card, and never uses it - not because he has previously had problems with overspending, I think it is just because he doesn't realize how awesome rewards can be. Example: he buys all his diapers/formula/baby food for two kids at Target, and maybe a lot of other household goods as well, but had no idea that you could get 5% off and free shipping with their debit card. It isn't even a credit card, it goes straight to your bank account! He has been improving his financial situation overall - putting more into his 401k, debating changing from a target date fund with 0.7% fees to the S&P 500 fund with 0.07% fees, asking me about IRAs, paying down extra on his student loans, etc. - but I just wonder how much more he could be doing with almost zero effort.
4) Yet another coworker, who is always just a little behind (her husband just got back from a deployment and hasn't been paid yet or gotten a new job, so ok) is leasing her car, has a subscription to one of those food-box delivery things for your meals at home (because she's working 10 hr days and is too busy), also has a subscription to a snack box delivery for work, ALSO has a subscription to a "we'll send you 5 cool new makeup/skincare/beauty items a month!" box.
Death by a thousand cuts, man.
It really has made me try to take another look at my own spending and habits to see what I'm missing. I know there are some obvious things (cell phone bill, not biking to work), but there must be other things that would be easy fixes that I just can't see.