This poem was written in 1940 as America was getting ready for the coming war by training women as CW operators.  33 is a CW prosign, like 73 which means "best regards" or 88 which means "love and kisses".  The prosign 30 that you see at the end of the poem simply means "the end".
Original author is unknown

Clara had her ticket
She also had a rig
Because she was just startin
It wasn
t very big.

She slowly tuned the crystal,
And watched the meter drop.
Then tapped the key a couple times
To be sure it wouldn
t stop.

Now everything was ready.
She called a short CQ
And received an answer
On thirty-six sixty-two.

They chewed the fat „bout stuff and things.
„bout dresses, work and dates.
They finally called it QRT
The girl sent eighty-eights.

Clara thought it might funny
Whether it be Miss. or Mrs.
To end a perfect QSO
By sending “Love and Kisses”

It sounds too sentimental;
Just a little too much “goo”
To be sending “Love and Kisses”
To a girl the same as you.

For an entire week she pondered;
t even touch the rig.
She pushed her slide rule by the hour,
Employing “logs” and “trig”.

She added and subtracted.
What could the answer be?
To reach a happy medium
Twixt eighty-eight and seventy-three.

Clara finally looked up from her work
All smiles and not forlorn.
Twas July in Nineteen Forty
That thirty-three was born.

s no real definition
But it
s meaning is known well.
s how a YL says good evening
To another friend YL.