LSE attempts some Biology

I'm being studious at the moment by watching recorded stats (optional) extra lecture. It's such a pity that I missed watching it real life! The lecturer likes cracking some minor humour to keep the bunch alive. For example:

The big circle depicts an "egg"(biology teachers would have killed me if I were to use that term) and next to it are the 4 sperms. Yea, he's doing probability on XY and XX. Reminds me of the good ol' science times! :D

& not to mention the other innuendo-s. Weirdly enough, the maths lecturers are always the ones who try to make jokes during lectures! Or maybe the friendly ones are the ones that I've got...