The mouth can only be opened while the "meat device" is preparing to "dump its content". Once the "content" is dropped and swallowed, you can open the mouth again one more time.
I would suggest it be actionable at all times once unlocked.
I thought it might be something to action after pulling out the meatstick, but once I did (for either meatstick option) everything else on the top bar became an X, leading me to think I no longer could.
Second bug report: I can't re-launch the game after ALT+F4ing it. I was going to try what you said to do, but it won't launch at all.
There were about 5 "XXXXXXX.tmp" processes running in the background that after I killed them the game was able to launch.
I tried an ESC close, and the game relaunched fine. I ALT+F4d close, and the game *still* relaunched fine. I don't know why the temporary processes stuck around. Possibly because I first launched the game from within the ZIP?