Stop at the Esso sign

At high school we went on many trips
Mostly to Adelaide: our capital city
We saw the play Eqquus: a bit risque
Full frontal male nudity on the stage
We were a bit shocked to say the least
Afterwards as we toured the city
We had a lunch break down by the River
I remember laying down on my belly
Enjoying a bit of lovely sunshine
Suddenly our teacher was taking my picture
(A picture of my bottom to be precise!)
I was wearing a pair of blue jeans
I had a pretty nice little butt back then!
Later back at our school in Loxton
All the trip's photos were on display
With added quotes from our teachers
Mine said "Stop at the Esso sign!"
They'd written a little Esso sign on my pocket!
That was one of the quotes from the play
The character kept on repeating and
There it was up on the board: 
My blue Jean clad bottom on display!