Having cold showers, stamp collecting, making daisy chains, training to become an overated midget DJ by the name of Mix-Master Compact (I got the name from a blender) but my favourite hobby would have to be remembering as many decimal places of pi and Euler's number, aka e.

So far I've got up to 300.

2.7182818284590452353602874713526624977572470936999
595749669676277240766303535475945713821785251664274
274663919320030599218174135966290435729003342952605
956307381323286279434907632338298807531952510190115
738341879307021540891499348841675092447614606680822
64800168477411853742345442437107539077744992069