Ianto's eyebrows soar. It's not so much that he's been one-upped (he knew the Doctor would have better stories than fireworks in a toilet tank. No question whatsoever.) It's more that destroying gravity fields that are keeping planets in place sounds precisely like the sort of thing Ianto would expect, but...

"...Whatever did the department store do?"

He scrounges up a scoop and taps a carefully measured quantity of coffee onto the filter, checking the temperature gauge. It's certainly all going well so far.