They each bought a pair of skimpy briefs, sporting a Superman logo, and had agreed to reveal their underwear to the crowd if either of them scored against Sunderland on Monday.
Although Richards was then ruled out of the game by a knee injury, Ireland kept his side of the deal after hitting the only goal of the game.
Richards said: "I was supposed to do that celebration with him. We both bought the same pants at the same time. However, I was not playing - and I am quite pleased now because otherwise I would have got the same stick.
"It was quite disappointing to hear people wanted him to be fined. You have to be so careful nowadays with how you celebrate because it seems that the fun element when celebrating goals is disappearing.
"It is not as though he was naked or anything and it was not hurting anyone so I do not really see anything wrong with it."