잖아요

"you know, right?" — shared knowledge

Ends a sentence to remind the listener of something the speaker assumes they already know or will instantly agree with: 수리비 정말 비싸잖아요 is "car repairs are so expensive, you know", 잘 썰었잖아요 is "you were great with the pies, remember". It is the everyday way of building a shared footing before making a point, which is why hosts and guests use it constantly. Said to someone who genuinely doesn't know, it can sound like you are correcting them. The casual form drops the 요: 잖아.

Register: polite conversational; 잖아 is casual