Last one I promise...
Paddy and Murphy are walking down the street when Paddy stumbles upon a discarded mirror on the path. he picks it up and studys it in silence for sometime before Murphy ask's him what's wrong. Paddy replies "Oi'm just tinkin', oi know dis fella but oi cant put a name to the face". "Give it here" says Paddy "ya daft eijit - it's me!"