Before anyone thinks I am being funny dogs are my special interest.
I have 4 dogs who live with me and my partner, they are quite used to being leaned on or suprised by their people, we have spent a lot of time acclimatising them to the fact that such actions mean them no harm as dogs are not naturally a cuddly species.
My worry with this picture is that sometime later it will turn into the "it suddenly flipped and bit my kid!" That you see on all the papers headlines. Why do I think that?
I'm sure you have been in situations where you have not been happy and have been unable to communicate but didn't feel like you should move as being still is what was expected? Imagine though you had a teenager standing on you (your larger than a dog remember) you could hurt him if you move, you give out subtle signals to say you are uneasy and they are missed, what is your next option? It's not like you can just get up and walk away, you have someone standing on you.