FB Flex Day 3 Complete + Most Painful Upper Body Exercise?

Hey there Blender Peeps!

So I just completed day 3 of FB Flex and the first day of Chocolena's Pulse Challenge. Anyone who wants to join that (https://www.fitnessblender.com/community/discussion/21042/feel-that-pulse-challenge-week-1-schedule). I don't know about anyone else but the pulses in this one were...wow! I had to pause the video everytime to finish the 5 sets. Kelli did it like it was nothing. Kelli? What is your secret? 😂

So there were actually two workouts: the main workout (https://www.fitnessblender.com/videos/at-home-abs-and-upper-body-workout-bodyweight-only-upper-body-and-core-workout) and an extra credit workout (https://www.fitnessblender.com/videos/at-home-upper-body-workout-for-toned-arms-shoulder-and-upper-back). I did not do the extra credit because I'm sore from day 1 so I only the main routine. Luckily, there was bodyweight option with Kelli and an option to do weights with the Daniel so I obviously did the bodyweight with Kelli. That is something to keep in mind: If you're sore (depending on how sore you are) and can still do a routine limit your range of motion and/or do the bodyweight options. DON'T overdo it.

Doing this routine I realized there was one exercise in particular that always gets me everytime and out of all upper body exercises I have ever done this one has put me in the most pain...and I LOVE it! I know you guys are curious about which exercise it is. No it isn't rows, nor flys, not presses nor pullovers nor raises or anything like that. It's like Kelli always says "This exercise is HUMBLING." This exercise in particular I love and it's amazing no matter how much you do it the soreness it leaves you in.

Anyone know which exercise I'm referring to? Do you think it's the most painful? If not, which upper body exercise leaves YOU the most sore?

Edited