Automatically lock screen if I leave the MacBook
We have the same culture in one of the environments in which I work. . . it's ruthless, so I know where you're coming from.

It's a good habit to get into to lock your screen whenever you leave it unattended, and soon you won't be on the hook for buying anymore pizza.

I find it helpful to set a "Hot Corner" for this.

Go to Preferences > Desktop &amp; Screen Saver > Hot Corners


chose the corner of your liking, and set it to "Lock Screen"


I use the lower right, for example, and just sweep my mouse to that corner whenever I am about to stand up and walk away from my desk.  Easy peasy!

You can also set the hot corner to "Start Screen Saver", but then you will need to set the following as well:

Also under Preferences > Desktop &amp; Screen Saver


choose the screensaver of your liking, and set it to come in withing
a comfortable amount of inactivity.  (Realize, of course, that if
you're reading something of length, and not moving the mouse of
interacting with the keyboard, your screensaver may engage while
you're reading/thinking/daydreaming.)


Go to Preferences > Security &amp; Privacy


under the "General" tab, ensure that the option to require password
"after sleep or screen saver begins" is selected.  Set the timing
option to "immediately".