The Joke :
The MacTavish brothers decided that one of their number would go to America and make his fortune, coming back to share with the rest of them. The youngest, Ian, was chosen for this task. Off he went, and he worked hard in America, and earned himself a fortune over a few years, and wired his brothers that he'd be returning with it. When he came back to Scotland he got off the boat, and looked around for his brothers, but could not see anyone who looked familiar. Finally, a group of bearded strangers approached. 'Ho, Ian, are ye not knowing yer own brothers?' asked the first one. Then Ian realized his brothers had grown beards.
'Fer heaven's sake, laddies, what would ye be growin' them beards for, now?' he asked.
'We had to, lad, ye took the razor wi' ye!'