I know I've already gone into "I wish you all the best" but here are some others:
1. "You look great." Perhaps because I've been pretty since 8th grade (once I got my braces off) and hot since college (when I had a "free" gym membership on campus), this one never made sense to me. Of course I look great! When have you seen me not look great (unless I'm sick)? If I'm out in public, I'm probably looking good because other people (maybe an ex!) will see me! I'm at an event for work (want to look professional), out with my friends (want to make sure we look like a cute gaggle of girls), or on my way to a date (need I say more?), it doesn't matter the situation: I'm going to look good, so don't sound so surprised when you see me and your fantasy of me becoming fat and ugly hasn't come true.
2. "I'm happy for you." This sort of goes along with the "wishing you all the best" thing. I don't really care if you're happy for me. I'm happy for me, and that's all that matters. And as for whether I'm happy for you, I'm pretty apathetic about the whole thing. You're no longer a part of my life, so it doesn't really matter to me if you're happy or not. It's none of my concern, none of my business. So I'm not sure why you have any joyous feelings for me...They aren't reciprocated.
3. "Are you seeing anyone?" How is that any of your business? We're not together anymore, which means you don't get to know about my personal life. We can talk about our jobs, the weather, a local sports team. But my love life is off limits. Plus, why does it matter to you? If you're trying to get back with me, you can kiss that dream good-bye: I don't believe in second chances. And if you're just curious, you clearly need to grow up and move on. I'm not interested about if or who you're dating: I'll mind my own bees' wax. Plus, there's no way you upgraded, so you're the one with the short end of the stick, not me.
Anything an ex has ever said to you that boggles your brain?