Sheikh is wearing a tuxedo (the coat men usually wear on weddings) considered imitation of the disbelievers? I'm confused what's considered imitation of kuffar? Is it only restricted to religious matters? Or can even saying certain slangs be considered imitation of kuffar?

Ustadh AbdulAziz al-Haqqan
Habits are included as well akhi. As for tuxedos Allah knows best.