I had two attempts:

Morph -> BBC -> BBC Controversies -> Conservative Party (UK) -> Political Sleaze (UK Politics) -> Cottaging -> Sex -> Sexual Intercourse

(7)

Morph -> Stop Motion -> Animation -> Adult Animation -> Cartoon Pornography -> Pornography -> Sexual Intercourse

(6)

Top choice of Morph as the start article.

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Edit: Well done rubah. I tried going through Tate Modern but then realised how little I knew about art to get much further.