"I'll find something," John begins , but Ianto is still struggling and that's frustrating. He lets out a sharp breath of irritation and gives Ianto a shove toward the wall so he can pin him, lifting his gun again.

"All right," he says finally, "if you really know so much about me why don't we prove it?"

Which will mean he needs to ask something that isn't public knowledge. What is team look like, their names, Atlantis -- that's all things that someone setting him up could easily know. So John tilts his head, and instead asks:

"When's my birthday?"