[hasbroslasher]

r/iamverysmart - funny screenshots of the Dunning-Kruger effect and people generally thinking they're God's gift to intellectual life.

r/holdmyredbull - extreme sports cousin of "hold my beer". Other fun ones in this circle include "hold my juice box" and "hold my fries". I tend to think of watching someone go skydiving without their own parachute as universally interesting, ymmv.

r/AskReddit - Good survey of the current human experience, usually leave here with a feeling that your questions about the world and lives of other people aren't as unique as you though. Sometimes it's banal/off topic, though.

r/ELI5 - "Explain like I'm 5" usually contains layman's questions about science, maths, history, and other sometimes unapproachable with great responses from people who know their stuff. Almost always leave here with something new to think/talk about.

r/ProgrammerHumor - I'm a programmer, but even some of my non-programmer friends can enjoy the jokes over here.