make a wav file recording, something like "thats a sh*t constraint" and name it connect.
when your friend goes for a coffee or smoke, jump on his machine and go to somewhere like
C:\Program Files\Autodesk\Inventor 11\Bin
and paste your wav file in, overwriting the original. then turn on constraint audio notification in aplication options...
sit back and watch next time hes working in an assembly...
lots of fun to be had :0P
Stephen Gibson