I asked at a bank recently for 100 $2 bills (I needed it for tipping on a cruise ship). The tellers were extremely curious about what it was for. I got 100 still-bundled bills, like in crime movies!
If this isn't something tellers see quite regularly, then what do other cruise passengers do? I asked for a lot of £5 (smallest denomination note in UK) at the bank once because I was going to a music festival (before mobile card payment was routine). They asked me casually why I wanted them and I explained. Seems to be a Know Your Customer thing.
The banks often have the $2 notes, but you have to ask explicitly.