Screenshot of the desktop as desktop background + hide icons;
Sublime text with "sound" plugin, for every action (ex. save) create 10 empty sound files and one with a whispering sound (you can save it from a whatsapp voice message), this way randomly 1 out of 10 the user of sublime text will hear a sound but won't understand;
Middle finger on the link cursor;
A piece of post-it or tape under the mouse covering the laser;
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Some ideas for you folks that I personally used: