Have you ever had a player, or even all your players, sit down at your table with a strong desire to do mischief? They want to insult authority figures, behave inappropriately, and cause as much chaos as possible. Kind of like a Marx Brothers movie.
Which might be great if you're running a comedy campaign. Or a comedy one-shot adventure. As a GM channel your inner Margaret Dumont, act snooty and outraged, yet never stop the players from making ever bigger fools of everyone.
But what about when you have a more serious campaign in mind? Must the rogue try to steal the crown off the kings head in full view of his guards? Must the pilot flush the starship's sewage over the coronation procession? Can't they just try and get the plot hook from the NPC instead of trying to convince her to marry the party's goat?
Part of what the players are reacting to is they never are supposed to be inappropriate in social situations. Kill the monsters, but always play nice in town.
If you let them have their fun once in a while, they are more likely to treat the rest of the campaign with the seriousness you wish. Well, you can hope.
Example: Ruin the Feast
The characters meet an NPC who will reward them if they agree to ruin the Imperial Feast. The Emperor has sent a young lord to the city state, with instructions to throw a fantastic feast, everyone invited. Free food! Free drink! Surely everyone will think highly of the Emperor after such a feast. (And maybe when the Empire moves to annex the city state, people won't get too worried.)
The party's job is to make the feast fail. Go around the table "What do you do to make people really remember this feast?"
The players will come with all sorts of interesting ideas. If it's not a slam dunk, have them role dice to see how great their idea worked. Fail forward, but if they role bad, they are seen by the young lord's servants.
At this point your trouble makers will be in heaven. "I tell the knight that his lady is sleeping with the young lord." "I hallucinate cockroaches and giant centipedes crawling out of the food, then use my powers to share my hallucination with others." "I'm dressed in my holy robes and I fire my halo up. Then I go behind people and push and kick at them. When they turn, I accuse others to cause fights." "'Poison!' I yell. 'They've poisoned the wine!'" "I animate the roast chickens and have them march up and down the tables. Roast chicken zombies!"
Note that this is a visiting lord who is getting the Marx Brothers treatment, not the PC's patron. Factions are great for this. Every faction has it's pompous leaders who are the perfect foils for PCs going wild.
Give the players a moment to laugh, then in a more serious tone open your next scene. If you need to focus the group, go ahead and be transparent. Tell them "This is a more serious scene. The stakes are high and you might not survive if you don't concentrate. Don't worry, if you liked the feast, we'll have similar scenes as the campaign progresses."