Under the leg, or UTL for short, refers generally to one having a masty under the leg. If you are unaware of the word masty, then fuck off. However, every day tasks are also done under the leg for amusement.
'Aw mate, I just had an under the leg in a primary school'

'Pat a strangers dog under the leg'

'I'm just heading home to have a UTL'
by Simonsmp May 16, 2010
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