Sherlock isn't very good at insults.
Freelancer
"You disgust me, Mycroft."
"Yes, well, I didn't make Mummy cry at my last visit home, did I? May not be a good idea to call me a 'pumpkin-haired lard ass'— for one, my hair is brown and two, my diet is going excellently, thank you."
"Your brother is a criminal mastermind?" asked John, causing the brothers to pause and stare at him. Mycroft looked mildly affronted.
"Minor position in the British government," he reminded.
"He is the British government," replied Sherlock scathingly, "when he's not busy being the British Secret Service, or the CIA on a freelance basis."
Prompt was #50: pumpkin