Office fly-tipping

Discreetly depositing one's workplace detritus at different bins around the office. Reasons for doing so include smell of lunch remnants, lack of one's own bin, producing too much paper based waste, to annoy work colleagues, for spite.

Simon: What were you doing in payroll?
Will: I was office fly-tipping.
Simon: Teriyaki don?
Will: Yessir.

Pocket drums

The rote act of briefly patting one's pockets when exiting public transport to make sure a phone/wallet/key is not left behind.

Just before Will stepped off the Tube he played pocket drums and, safe in the knowledge he hadn't left anything in his seat, he exited the train.