Nothing in a game of D&D has ever made me question my friends' intelligence like the time he was a lawful stupid paladin, and I was a chaotic evil pathological liar with a literal god-like power to not just use deception in a realistic way, but would magically make any lie that succeeded fully believed by the affected individual. I basically could only lose a sense motive check against me if I rolled a 1. Paladin player can see my character sheet since it's all on the Roll20 system in game attached to my token, and there is no possible way he could ever win a sense motive check against me; but he would still try every. Damn. Time. My character would speak. It wasn't even the metagaming that annoyed me at that point. It was the lunacy.
The +16 Persuasion Silver Dragoness one of my players made (+6 cha, Expertise, level 13 total. Playable dragon template) is extremely funny because there's an entire evil organization trying to convert her to working for them and she's convinced 2 of their 5 top brass that instead of her defecting to them, THEY should defect to HER. The others are more firmly evil but honestly it's by far the funniest way to deal with the mafia I've ever seen
You see it - an ambush. Four with crossbows, watching from the shadows in upper story windows. One leaning against the wall forty feet ahead with his finger twitching nervously over his knife. Three at a table, barely visible through swinging saloon doors, but each with a hatchet in hand listening for the sound of fighting. You feel every grazing shift of the wind, hear the distant crake of carrion crows unaware of the feast that is about to be laid out.
You see beyond the walls of the buildings, even. No, beyond... something else. Another kind of wall. One distant, but ever-present. Five titanic figures, shrouded in the haze of vast distances, looking over you. They speak, but you cannot know their tongue. One commands the others, a theatrical gesture wrought across the entire sky, and the other four hurl stones of mountainous proportion. What calamity have you witnessed?
And in an instant, they vanish from your sight. One of the crossbowmen shot your leg.
Expertise doubles proficiency bonus, so it can't be odd--so the +9 is both proficiency bonus (x2) and ability modifier. Since bardic inspiration is a d10 here, the characters are level 10-15, so PB is +4 or +5. It seems OP's character only as a +1 charisma mod. Or, less likely, the character is lower level with a +3 PB and a +3 CHA mod grouping with a higher-level bard.
Lower level and a high-level NPC bard gave the inspiration. Unsure whether he gave it to the NPC I was up against; if so, the guy flubbed that roll too.