This is going to consume me.

All I can hear is a can opening, like when it doesn't pop open right away. I will not rest until I uncover the truth and you get paid.

Maybe dropping a piece into the board in Connect 4?

That's my first official guess.

My new guess is... some kind of toy gun or cheap plastic bb gun or something similar.

Like the sound of loading the clip in and then pulling back the slide to load one in the chamber.

My guess was already guessed. Shuffling cards. I hate this game so much. Loading a shaving razor would have never come to my mind, even if given until the sun burns out to figure out the answer.