An all time classic

Three male Labradors , one chocolate, one yellow and one black were sitting in a waiting room at the vet's when they struck up a conversation.
The black Lab turned to the brown Lab and said, 'So why are you here?'. The brown Lab replied, 'I'm a urinator. I urinate on everything.... the sofa, the curtains, the cat, the kids, but the final straw was last night when I urinated in the middle of my owner's bed.'
The black Lab said, 'So what is the vet going to do?'
'Gonna cut my nuts off,' came the reply from the brown Lab, 'they reckon it'll calm me down.'
The black Lab then turned to the yellow Lab and asked, 'And why are you here?'
The yellow Lab said, 'I'm a digger. I dig under fences, dig up flowers and trees, I dig just for the hell of it. When I'm inside, I dig up the carpets. But I went over the line last night when I dug a great big hole in my owner's couch.'
'So what are they going to do to you?' the black Lab inquired.
'Looks like I'm losing my nuts too', the dejected yellow Lab said.
The yellow Lab then turned to the black Lab and asked, 'Why are you here?'
'I'm a humper,' the black Lab said. 'I'll hump anything. I'll hump the cat, a pillow, the table, fence posts, whatever. I want to hump everything I see. Yesterday, my owner had just got out of the shower, and as she was bending down to dry her toes I just couldn't help myself. I hopped on her back and started humping away.'
The yellow and chocolate Labs exchanged a sad glance and said, 'So, it's nuts off for you too, huh?'
The black Lab said.... 'No No, I'm here to get my nails clipped'.