Can I post a non-bawdy one, please, that happens to be my favourite limerick? It was composed by a very brilliant pupil I had who was founder/secretary of the school Astronomical Society for their magazine, which natch he also edited, in my long-ago [retired 25 yrs since] teaching days.

Apollo to Mission Control:
We are almost in reach of our goal —
But this reading of G
Seems excessive to me
And I think we are near a black