word choice - Do you "slump on a bed" or "slump onto a bed?"

Is one of them the correct option? Or they mean different things?

On Google maps I got these results:

"slumped on the bed" (9K results)

"slumped onto the bed" (3K results)

Example sentence:

Without permission, he slumped on/onto my bed and lay on his back.

Answer

You can do either.

To slump is to ease from an erect posture to a relaxed one where the shoulders are hunched and there can also be a bend at the waist.

If you slump on the bed, you're on the bed, slumping.

If you slump (down) onto the bed, you come to rest on the bed as the end result of your slumping.

That's the basic difference of on and onto.

But some speakers may use on to mean onto.

He jumped on the stairs of the train as it began to pull out of the station.

He jumped onto the stairs of the train as it began to pull out of the station.

So, given this variation in usage in the speaking population, you cannot be sure exactly what is meant if the preposition is on in this context.