Good of Ianto to provide a convenient target for his sudden ire at being unable to find...something. For a second he's afraid he's forgotten what it was, but the absurdity of Ianto's suggestion reminds him. He glares like Ianto has offended him down to his soul by being so unhelpful.

"Don't be stupid, there were never any can openers in the TARDIS. What nonsense." There's something else bothering him about this, something he can't work out quite yet, but it'll come to him any minute.