Believe it or not, this is Lilly's 'come hither' look.
Every three weeks when she is in season she uses this neck stuck out, gnashing and drooling (yes that is drool in the bottom left pic) stance to drive the boys wild. I wont tell you what goes on at the other end, but think wink! Fortunately none of the the boy donks are still equipped to do anything 'productive' about it, but it doesn't stop them trying.
Angus Donk and Jack follow her around possessively, warning each other off with hooves and teeth, and occasionally mounting her (TMI?) Joey Boy is possibly the most inert donk in the world, so just gets on with grazing, whilst probably wondering what the other fools are up to.
I have learned that taking a them out for walks when Lilly is on heat can have very embarrassing consequences!
Poor Jack to try and keep up with that.