Falconry, that is. Now that peacay has posted from The Book of the Hunt of King Modus & Queen Ratio (what are you waiting for – click through – I’ll wait) I can turn this little bit of goofiness loose.
N. B. I discovered the image only because peacay pointed me to the book pre-post – all credit redounds to him and all blame to me.
And some explanation for non-falconers: sure seems like the protagonist is trying to whup on one of his hunting companions with a lure. A slip is a chance for a hawk to pursue game – it can be screwed up innumerable ways, but mostly by flushing game before the raptor is in position.