It's on me. My treat.

May I invite you out to lunch? (午饭) May I invite you out to dinner? (晚饭)

domasla wrote: "May I invite you out to dinner?" My reply: I'd say that's got a wee pleonastic ring to it. You INVITE someone out to dinner, and then TAKE her/him out to dinner. So, your friends might say: "He invited her out to dinner." But you, the one doing the inviting, should probably say: "May I take you out to dinner?" Besides, "Taking someone out to dinner" is more idiomatic, too.