What’s wrong with directly asking? It’s not like it can cause a problem.
If he’s a normal, caring guy, he’ll just say “sure” and do it. If he’s a guy like me, he’ll laugh and come up with an ornate way to make you regret ever asking for such an indulgence, thus giving you the kind of attention you really crave. And if he’s just a dick, he’ll throw a fit and show his ass, making it easy for you to decide to get the fuck away from him.
Clear communication works, and is seldom a bad idea.