I love playing chess. Someone at work had the idea of having a chess board at work and slowly play a few moves when we have free time. After work he stopped by and we sat down and played a bit. It was his move and right away he did something. . .that would be bad for him.
My dad kind of taught me with the mindset that when playing a friendly game, it's nice to point out when the queen is in check. He moved a piece that would let me take his queen, so I let him take his move back as he hadn't noticed.
Only a few moves later (1. e5 b4 2. Nd5). . .he considered the following to attack my Knight.
Qb5? I was wanting to navigate my Queen's knight up the left, but was busy doing other things so it wasn't until his pawn attacked it that I moved it. So I already had a plan in mind on the left side. He held his finger on his Queen and I already could see what a bad idea it was. He did move his Queen back and examined the board, I decided to be nice again and comment: "That would have been a terrible move." to discourage him from doing it. (When he was like, "What, really?" I grinned and said, "Do it and I'll show you!")
He was being pretty hasty, so I wasn't surprise that he didn't see it right away because, again, I already had a plan in mind for that side of the board with my knight. But after mentioning it, he still didn't see it. I was a bit amused and I wanted to show him how, but I couldn't. (Not until later.)
So if Black moves Qb5. . .can you see White's best move? Hint: It puts black in Check and guarantees material for White.