A barman, two ponies and a blonde

A blonde enters a bar and asks the barman,
“Oh! Sir! Please! Can you help me? I have just bought two ponies but I can’t tell them apart! What should I do?”
“Why don’t you chop off one of their tails,” the barman replied. “That way you could tell them apart!”

So the blonde left, and came back a month later and said,
“Oh! Please! Can you help me again? Cutting the tails really worked but they’ve grown back! What am I to do now?”
“Why don’t you chop off one of their manes,” the barman replied. “That way you could tell them apart!”

So the blonde left, and came back a month later and said,
“Oh! Please! Can you help me one more time? Cutting the manes really worked but now they’ve grown back. What can I dow now?” She cried in despair and frustration.
“Okay then,” said the barman, who was beginning to get annoyed with the blonde. “Why don’t you measure them?”

So the blonde left and came back the next day.
“Oh thank you so much! Now I can tell my two ponies apart always! The white one is taller than the black one!”