What's with the gold?

A man walks into a bar and sees a pot of gold. Curious, the man asks the
bartender what is with the pot of gold.

'Well, you see every day I give a challenge and whoever can complete the
challenge gets the pot of gold.' 'What's today challenge?' 'You see that
donkey. You have to make him laugh.'

The customer says, 'Do you mind if I take him out back?' 'No problem.' The
customer takes the donkey outside and in a few the minutes the guy walks
in with the donkey, and they're laughing up a storm. The guy finishes his
drinks, takes the pot of gold, and walks off.

Next day, the same guy walks in and sees another pot of gold. 'What's
today challenge?' 'You have to make the same donkey cry.'

'Mind If I take him out back ?' 'Sure' The guy takes the donkey out back
and in a couple minutes, they walk in with the donkey crying his eyes out.

The guy reaches for the pot of gold, but the bartenders says, 'Wait, first
you have to tell me what you did do that donkey yesterday and today.
'Fine. Yesterday I told him that my dick was bigger than his and today I
proved it.