I for one would be happy if someone made a simple digital watch (time, date, batt, BT -if on) with this background:
If you would want go high tech you could make the "Ha ha ha haha" -text like a move bar... the longer you go without moving, the more "Ha ha ha"'s
A no "Ha ha ha" -version:
http://jodahome.com/wp-content/uploads/2015/07/Best-Joker-Wallpaper-HD.jpg
Preferably to fenix 3 and f3hr...but why not also other models.