What is the ruling on saying "trousers are Sunnah," and is this considered a degradation of the Sunnah? And is it permissible to tell a joke like, "A stoner stayed up all night thinking. His brother asked him, 'What's wrong?' The stoner replied, 'There's a question that really puzzles me'"?

Wearing trousers (sirwal) is a confirmed Sunnah of the Prophet, peace and blessings be upon him, for he bought them, wore them, and commanded their wearing. This indicates that stating that trousers are a Sunnah does not constitute belittling the Sunnah.

As for lying for the purpose of joking, it is forbidden, whether it is to elicit laughter or for any other purpose, due to the Prophet's saying, peace and blessings be upon him: "Woe to him who speaks and lies to make people laugh; woe to him, then woe to him." Lying is forbidden in Islam in all its aspects, and one must be wary of it in all circumstances. This cannot be compared to permissible lying for educational purposes, such as proverbs and wisdom, because lying in jest has no benefit, no knowledge, and no wisdom.