Just started doing this over the last couple of days:
Put kettle on to boil for whatever reason (fill the kettle to near maximum capacity).
When you put it on, start running as hard as you can on the spot.
Keep running on the spot, getting your knees really high and your arms pumping for the duration of the kettle boiling. As the kettle takes about 4 minutes to boil, I like to visualise myself as a classic middle distance runner like Hicham El-Guerrouj or Kelly Holmes.
Stop running when the kettle finishes boiling and get back on with your life.
What other random exercises do you do round the house?