If you are typing ls, but in a hurry or by mistake typed sl, then this little program will visually tell you that you are wrong 
Based on the wonderful and funny good old SL (Steam Locomotive) by Toyoda Masashi. Only instead of a D51 steam locomotive, a fossa flies with a smoking cigarette in his mouth and a jet pack on his back
I think 's' would mean 'smoking', but let someone come up with a second word for the letter 'l'.
You don't even need to run anything, just make a mistake and type sl instead of ls in terminal You can change the trajectory with sl -F
Here is the .pet:
sl.pet- (5.63 KiB) Downloaded 21 times
