Use the four-part test
A good punishment should be agreed to in advance, limited in time or cost, safe to complete and funny to the person losing as well as the person winning.
Avoid humiliation as the entire joke
Public embarrassment can feel funny when everyone consents to it, but it is a poor default. Choose consequences that create playful inconvenience instead: cooking a meal, wearing a rival jersey, doing a chore or recording a short concession speech.
Match the punishment to the relationship
Longtime friends may enjoy sharper trash talk than coworkers. Couples may prefer a date-night or household stake. Family leagues often work best with harmless traditions. The punishment should fit the people, not an internet list.
Give people an escape hatch
If somebody becomes uncomfortable, change the stake. Fantasy football is optional entertainment. Protecting the relationship and the league matters more than enforcing a joke.