Seamus is having a bit of trouble seeing things at a distance so he goes into an opticians for an eye test. The optician asks him to cover his right eye with his left hand and read the letters on the card. Now Seamus has always had difficulty telling right from left so the optician says not to worry and to cover his left eye with his left hand and then read the letters on the card but still Seamus has problems.
The optician, being a helpful chap, has a brilliant idea and taking a cardboard box, cuts out two small square holes and puts it over Seamus' head with the words "there, now cover up one of the holes and read the letters on the card through the other hole." Seamus however bursts into tears and the optician becomes very concerned, takes the box off his head and askes why he's crying: Seamus replies, "I wanted a metal frame like me brother's got".