[27F] My [31M] boyfriend has been making nonsense noises during sex and otherwise. Help?

My boyfriend is making normally funny, complete nonsense noises and words during sex. I love him to bits and I just want it to stop so we can get back to normal.

To give some background, we're both living together in Manhattan, and we moved in together last year. I'm a dual UK/US citizen and he's originally from Hong Kong, but has genuinely lived everywhere growing up (Singapore, Auckland, Panama, and other places). We immediately hit it off when we met simply because of our international backgrounds and mutual understandings.

My boyfriend has a fairly relaxed, blasé approach to life because he doesn't really have to work any more. His father left him an enormous sum and some properties when he died a couple of years ago (heart attack not too long after we started dating). He's also probably the most 'reddit' man I know that doesn't use reddit, and actually somewhat dislikes that I use it. Loves sci-fi, quotes Carl Sagan too much (he's a physicist), is a fairly militant atheist etc. But a lovely man who I think gets it from facebook, which means I'm safe from him seeing it here.

He has this sardonic and gnarled sense of humour and we like to make each other laugh a lot. Normally this comes in the form of jokes and observations, but recently he's started trying to scare me into laughing with these noises he started making a few weeks ago.

It's a bit embarrassing to admit, but normally he got it completely right. Things like 'flooby-nooby-woo', 'womp-womp', or 'morp' dropped randomly into our days, but never overdone. It sounds juvenile and stupid now that I'm reading it, but there's something about his demeanour and execution when he did it that made it dumbly hilarious.

It was still funny until about a week ago, when it began to become distinctly unfunny.

We were in the middle of having sex, just missionary, when he starts giggling. I'm a little irritated that his mind is obviously elsewhere, but I ignore it. Then he looks up at me with this wild look in his eye and goes 'tingle dingle'.

I completely lose it I'm laughing so hard. I laughed so hard I was flexing my kegels and he came all over the sheets and himself. He's laughing with that strange look and he rolls of of me. Lying next to me, in this weird giggly post sex haze he keeps doing it. 'Broop broop'; 'shabber dabber'; 'scoobert doobert' (which when I searched it came up with a meme page); 'brep'. They're always variations of these strong vowel sounds if they're double barrelled.

I get tired of it and ask him to stop, and he does, then apologises and we both had a nice laugh. But he still had that look in his eye.

Now every time we have sex he does it at some point, and I'm honestly a little scared. He also uses it to get out of conversations that he doesn't want to be in, for example:

“What did you do with the dry cleaning?”

“Ka-pa-brapapapa.”

And then he just walks away!

I've tried speaking to him about it, but it's no use. And he's completely normal, otherwise! I don't know if he's having a psychotic break, or he's enjoying it too much, or he wants to break up and he's pushing me away, but it's really driving a wedge between us that I have absolutely no clue how to approach. It's only been like this for a few days but he's become completely intolerable to be around, and I just leave now when he does it, which is maybe what he wants?

I'm incredibly confused, and more than a little bit hurt. My friends are mystified as well.

He's in the other room just now and I can hear him making the sounds, just to himself. I think he's playing on the xbox.

Has anyone seen something like this before? Is he having a psychotic break? Should I take him to a doctor? Psychologists? It's just so strange. I'd sort of like to show him this post so he sees how I feel...

I appreciate how odd this must seem, but I'm at a loss for what to do. Any insight is much needed, because I really do want to fix this without having to employ a relationship counselor.

tl;dr: My boyfriend started making strange noises like 'flooby-wooby' to make me laugh. Now he's doing it during sex, and to get out of difficult conversations. He's also become aloof and unconcerned. Help me?