Of course it kills the joke to have to explain things, but I'm just going to have to accept that fact that some of our younger visitors might possibly not pick up on this reference. The reference is of course to Peter joining the Avengers, and the confusion is with John Steed - the immaculatedly dressed English Gentleman hero of the 60's TV Show "The Avengers".
If you don't know what we're talking about, or even if you do and you feel a sudden pang of nostalgia, you can check out some links here, here, and here. Just please let's not mention that awful modern movie remake with Ralph Fiennes and Uma Thurman!