How do guinea pigs show submission?

[Beth-Joy]

We have a pair of young male piggies, and one of them (Rhubarb) will often show his dominance by making a low sound and moving his bum slowly from side to side. But then the other one (Schnitzel) often has this strange reactions - he places his head under Rhubarb's chin so that his face is against Rhubarb's neck. Is this a display of submission?

 

[Piggies&buns]

The swaying and low sound is called rumblestrutting
Submission is in the form of a loud squeal

These threads below explain boar and dominance behaviours

A Comprehensive Guide to Guinea Pig Boars
Dominance Behaviours In Guinea Pigs
Bonding and Interaction: Illustrated social behaviours and bonding dynamics

 

[Beth-Joy]

The swaying and low sound is called rumblestrutting
Submission is in the form of a loud squeal

These threads below explain boar and dominance behaviours

A Comprehensive Guide to Guinea Pig Boars
Dominance Behaviours In Guinea Pigs
Bonding and Interaction: Illustrated social behaviours and bonding dynamics

But do you know what the whole face in neck thing is?