I'll just include his losses in the UFC and boxing.
Here is my order, and reasons for it
1) Khabib
Now there shouldn't be any shame from losing to possibly the LW GOAT, but it was the constant cheating + relentless trash talk which backfired on Conor + the magnitude of the fight.
-During the lead up, Conor attacked Khabib's bus, told him he would have been dead if he got off, called him a glass jawed rat, called his father a coward, called him an amateur, basically talked an astronomical amount of trash
-During the fight, he was outgrappled, knocked down by a wrestler, taken down multiple times, ground and pounded and choked out. He was warned by Herb Dean many times for grabbing the fence and other stuff. As if the beating wasn't enough, one of Khabib's corner jumped in and sucker punched Conor too.
2. Nate Diaz 1
Conor talked mad trash, predicted that Nate would panic wrestle but it was the other way around. Nate definitely took away that aura Conor had after dethroning Aldo. Plus Nate had 11 days notice to fight, and Conor had excuses such as fighting guys 3 times the size of him
3. Dustin Poirier (3rd fight)
Poirier had a dominant position and pounded him on the ground quite a bit. I would have listed this as 4th most embarrassing, but seeing Conor's post fight interview bumped it into 3rd place. Threatening to take the fight outside like a thug, and yelling about DP's wife while slumped on the ground was pretty bad
4. Poirier 2 - DP is a beast, and Conor didn't talk much trash in the build up if i remember correctly, but fans still mocked him mercilessly
5. Mayweather in boxing - I don't think this was humiliating at all. For someone with a 0-0 pro boxing record, lasting 8 rounds with one of the greatest boxers in this generation is pretty good, even if Floyd carried him. This fight didn't affect his legacy or aura much, plus it made him richer than ever
That's my personal ranking of Conor's losses from most embarrassing to least. How about yours?