Quote Originally Posted by Kekvit Irae View Post
Open up notepad, save the blank file as "Prostitution Tycoon" (without the quotes). Go to your folder options and make sure known file extensions are hidden. Now go into Steam and choose Add Game and select the file you just saved. When you open it from Steam, you'll open up the blank notepad and everyone else will see the pop-up notification "Husar is now playing Prostitution Tycoon."
If you don't have file extensions hidden, it will say "Husar is now playing Prostitution Tycoon.txt." instead, which ruins the joke.

:)
Alternative:

Right click the game you want to play in steam (non steam game, so for me, something like Mount&Blade) click properties. You can change the icon, and the first box says the name of the exe it launches off. You can change it.

So right now, if I launch M&B, it will say Non Steam game Mount&Blade. I can change that to whatever I want, and still be playing M&B.