Display a "bullshit" stamp sign overlay at current mouse position for a configurable amount of time. One can also choose different images: bullet impacts, "refused by QA" stamp.
On Linux, you can have fun with xbindkeys. Install it, edit the configuration file as:
"cd /path/to/bullshit/ && ./bullshit.py"
control + b:1
Run xbindkeys. Now, "control + mouse click" should display the "bullshit" stamp.
Use it well.