What are some of the best recurring gags in otherwise very serious shows?

Stannis and his insistence on the use of proper grammar on Game of Thrones always made me laugh. He corrected Davos when he said “less” instead of “fewer” and Davos would then go on to use that line himself to correct others

Sawyer with his nicknames on Lost were also a real treat. The ease and cleverness of some of those nicknames always helped lighten the mood.