Without going against any safety regulations etc.. etc.. how many pilots do you know like to have a bit of fun in the air.
As an example, many years ago i was on Air 2000(at the time), now First Choice 757 from Manchester to Tenerife. The two pilots on board were in late 20's and ex RAF and Army pilots. On the way down, the Cap and FO were working out how to overtake another Air 200 aircraft by changing their routing to TFS. Once they had done the calculations and routing, they called air traffic to ask if the could route via x,y,x (cant rember the NAV points), anyway , what a surprise they were refused. But they had a good laugh for trying. As i say as long as it doesnt impair safety it seemed to keep them amused for 30mins