Since when do you (do something)?

When someone that you know well does something new that they've never told you about before, it can be surprising. When you're surprised by a friend, coworker, or acquaintance's actions in this way, you can say "Since when do you ___?"

For example, if a family member who usually doesn't listen to you suddenly asks for your opinion, you can say:

Since when do you care what I think?

If your friend who's never studied Spanish before tells you that he bought an Spanish grammar book yesterday, you can say:

Since when do you speak Spanish?

It's important that you understand this: you don't ask "Since when do you..." if someone tells you about something new that they're doing. You say this if they mention something that they've already been doing for a while, but which you've never heard about before.

Also, notice that each of these examples uses "do you" instead of "did you", even though they kind of describe the past.

This phrase appears in these lessons: