How was copper wire invented?
Two Scotsmen fighting over a 1p piece

Why is a 50p piece shaped like it is?
So you can get it out of a Scotsman's hand with a spanner

The angry wife met her husband at the door. There was alcohol on his breath
and lipstick on his cheek.
"I assume," she snarled, "that there is a very good reason for you to come
waltzing in at six o'clock in the morning?"
"There is," he replied. "Breakfast."

Brenda O'Malley is home making dinner, as usual, when Tim Connor arrives
at her door. "Brenda, I've something to tell you, may I come in?". "Of
course you can come in, you're always welcome Tim, but where is my
husband?" "Thats what I'm here to be telling you, Brenda. There was an
accident down at the Guiness brewery..." "Oh, God no, please don't tell
me", cries Brenda. "I must, Brenda. Your husband Shamus is dead and
gone, I'm sorry." Finally, she looks up at Tim, "How did it happen Tim?"
"It was terrible, he fell into a vat of Guiness stout and drowned!!"
"Oh, my dear Jesus! Tell me true, Tim, did he at least go quickly?"
"Well, no, Brenda...fact is, he got out three times to pee."