What does the term "first base"/ "second base" etc mea? I know the rough meaning (how far you have gone with your boy or girlfriend!) but what do the bases actually stand for?
The entire point of the little ditty is a play on words. Imagine someone who couldn't pronounce their rrrr's would say gland instead of grand. So the point of the last line is grand (wonderful).
Even if you are slow, I'll arrive late anyway. Shall we make it twenty past?