It's Always Sunny In Philadelphia: This Theory About The Waitress Will Blow Your Mind
3. Charlie And Dee Slept Together
Charlie and Dee sleep together in one of the most important episodes of the entire show. In The Gang Misses The Boat (season 10 episode 6) The Gang decide to take a little break from each other. Dennis wants to be more relaxed, Mac wants to be known as a Party Boy again and Frank, meanwhile, searches for another gang.
Charlie and Dee, interestingly, end up having lunch together. They are away from the judgement and pressure of the rest of the group and can be completely open with each other.
This scene is highly pivotal in the series because they discuss that very theme during their dinner. In a moment of total honesty, they reveal their fantasies and encourage each other to pursue their interests.
During an improvised Slam Poetry session, Charlie and Dee kiss and fall back on the couch together. The show heavily implies they sleep together based on the awkwardness the very next day.
Unfortunately, The Gang agree to reunite showing that whilst Charlie and Dee had realised their true feelings for each other, they'd rather suppress those feelings than explore them further.