I will start with the background. Robbie is a nuetered male (springer of course) 11-12+ years old. He is the daddy dog. Ernie is a nuetered male (ditto) 5-6 years old. I got them both at the same time from rescue. I told the people I wanted two, preferably an oldie and I wanted them to put them together before I picked them up so they would know each other before going to a strange home. I've had them allmost two years.
Robbie has a habit of licking Ernie all over. He will lick and lick and lick. He really licks Ernie's ears thoroughly. And he licks Ernie's boy parts.

Ernie allows all of it and sometimes stands so Robbie can do a good job.
It's like he is grooming him? He rarely does this to Chip, but Chip will let him.
Any idea what's going on?