I heard a new one today

[mike4]

"About as usefull as tits on a boar pig," was one of my foremans favourite expressions when it came to describing a new worker,
Michael

[hornluv]

"Hotter than two rats f*cking in a wool sock"

"Colder than a stainless steel toilet on the shady side of an iceburg"

[Jon Leary]

Those tires are so thin you can see the air in "em. If brains were gasoline he wouldn't have enough to prime the carburator on a piss ant's motorcycle.

[rollin45]

"got the personality of a blood clot"

[mich_88_13]

You're fuc*ing this cat. I'm just holding the tail.

[sasquatch]

"His elevator doesn't go right to the top!"

[38_Cal]

Sharp as a meatball.

David

[kyfho]

When referring to a particularly tough material -

"Harder than woodpecker lips"

[sasquatch]

"Hornier than a twin peckered owl!!"

[Gravy]

On a more cheerful note:

"Busier than a puppydog with two tails"