Last year I was with a group of cavers getting ready to go down Oxlow Cavern in Derbyshire and one of us, Steve, hadn't any water for his carbide generator. I saw a water trough in the field across the road and suggested he nipped into the field and get some water from the trough, about 20 metres inside the gate.
Unfortunately, I then spotted a bull in the further corner of the field who was walking quickly in his direction. Steve coudn't see the bull as he was crouched down at the trough and there was some sort of water tank on wheels obscuring his view as it was between him and the bull.
Steve, of course, thought I was pulling his leg about the bull! I told him it was now *running* in his direction and again he told me to "P*ss Off!" and continued filling his generator. However, he soon heard the thundering hooves and stood up!
He then realised I wasn't kidding. He broke the 20 metre sprint record and did a neat gate-vault, still with the carbide generator clasped in his hand, just in time as the bull arrived just behind and stood there bellowing loudly!
It was about 10 minutes before any of us could speak as we were rolled up with laughter!