Actually you can go to a bank and ask for $2 bills. Most good banks have at least a few of them, as people often ask for them for birthday gifts and such.
On the other hand, some older people think the $2 bills are bad luck.
In some smaller towns some companies will at some odd interval pay there workers with $2 bills just to show the community how much they impact the community.
But to really make shop keepers upset, pay with Sizie B's.