Spook when Spoken to

Here's the comic, a bit early for a change.

The GoHP (Ghost of Heartbreak Past) is trying to piece together the Sphinx's classical riddle "What walks on four legs in the morning, on two legs in the afternoon, and on three legs in the evening?" The answer is mankind, who crawl on all fours as infants, walk on two legs as adults and walk with a stick or cane in old age. Those of you who've read The awesome Mr Terry Pratchett's Discworld novel "Pyramids" may remember a far more amusing adaptation of this riddle. Looks like Anne is far from amused right now.