Pinched from a mate of a mate on facebook:
A great big seven foot bit of green tarmac walks into a pub and says, "Pint of bitter barman, and don't argue because i'm tarmac, I'm hard as owt. Cars drive over me all day and I feel nothing". The barman thinks, "Don't like the look of him", but serves the tarmac to keep the peace.
A few minutes later a seven foot bit of black tarmac walks into the pub and says, "Pint of bitter barman and don't give me any grief because I'm motorway tarmac and I'm hard as owt. Trucks drive over me all day and I feel nothing."
The barman nervously serves the bit of motorway tarmac.
Time passes and the two bits of tarmac stand at the end of the bar, have a few more beers, begin to get rowdy and start squaring up to each other.
"There's going to be bother soon", thinks the barman.
Then a seven foot bit of red tarmac walks into the bar. The green and black tarmac immediately quieten down and start quivering nervously. The barman goes over to them and asks them what is the matter.
The black tarmac whispers to him, "Don't serve that red tarmac - he's a cycle path".