Ralph: Listen, I've been meaning to ask you. Do
they tell you who you can date over there?

Mulambon: Of course not. I am the king.

Ralph: Damn. I knew I was
gettin' hosed (screwed over?)over here.
Next scene...
Phipps: Well, I think he did pretty well,
considering.(considering what?) It could have been worse.

Yes, he could have
exposed (removed his clothes?)himself, I suppose.
Yes, considering something, but without context we can't tell.

Exposing his position or situation is probably more like it, although more context might indicate that he was taking his clothes of.
Yes, he's getting screwed. Not that "getting screwed" is mildly vulgar, and "getting hosed" more so.

I don't let my children use "screwed" but I don't have a heart attack if they do. I'd stop them if I heard them use "getting hosed."

He's the king, so he shoudl be able to do whatever he wants, right? But instead, they tell him who he is allowed to date. This other king is saying, bascially, "Are you nuts? When you're the king, you get to do what you want and no one should tell you otherwise" so Ralph is realizing that this other king has better rules to live by than he does.
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What about the first blue, Philip?
 BarbaraPA's reply was promoted to an answer.
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GG, I've never thought of "hosed" as having any sexual connotation. I thought it just referred to, you know, a hose. Here are some various explanations of the term.

Apropos of kids and what they say, just the other night the kids were reminiscing about how after they saw Men in Black, (they were about six at the time) how upset I got when they randomly hollered, "Eat me!" "We didn't know why you told us not to say that, Mom."
Thank you both!