ちょっとシャワー浴びてくるって英語でなんて言うの？

"I am going to shower quickly." Quickly, fast, in a hurry, etc. You will be quick, not slow. The opposite would be, "I will be in the shower for a while." "I will take a real quick shower." You might use this expression if someone is waiting for you or will be coming to your house soon.

If you say "I'm going to jump in the shower and be out in a minute", it indicates that you will be taking a very quick shower. You might want to add "I will call you back when I'm done / later" just to indicate that you're getting off the phone. It would also be appropriate to say "I'm going to take a quick shower. Talk in a bit"

You are chatting on the phone and perhaps you prefer now to end the conversation and then take a shower. The first example sentence may seem a little strange to the listener. Are you so dirty that you cannot bare to continue the conversation further! Well, it could be possible. However, taking a shower is not really a good reason for ending a conversation. It's like saying: "Excuse me I want to go sit on my sofa now." It may even seem rude. But it does depend on the situation. It is quite common to give a better reason to stop speaking - such as sentence 2 or 3, which are a little more convincing than the first one.

To say to a person that you are going to take a quick shower, you can describe it by the length of time such as "I am going to take a short shower."

There are several ways to let your friend on the phone know that you need a quick shower. You can say: Sorry, but I need to take a quick shower and call you right back. I need to refresh myself. I'll take a quick shower and call you right back. I need to take a quick shower. Talk to you soon. A common phrase is: "Can I take a rain check?" It means right now I can't accept something but I can later. I need to take a quick shower. Can I get a rain check on our phone call?

I'll call you back, I'm just going to jump-in the shower! - 'Jump-in' which is a phrasal verb (in this context to take the opportunity). You can use this if a friend has just called you and you was just about to 'jump-in' the shower. The shower just became free, I'll call you back! - If you live with other people you can spend a lot of time waiting to use the bathroom. Regardless if someone was using the shower or not, it's a 'white lie' to end the conversation. As in "The shower just became free, I'll call you back later!"

If you’d like to explain to someone that you want to take a quick shower, you can simply say this by saying something like “Hold on, I’m going to take a quick shower.” Or “I’m just going to jump in the shower real quick.”.

Jiffy is an informal term for any unspecified short period of time. "I will speak to you again in a jiffy" Hop in the shower means "I'll take my shower and get cleaned up quickly." A Quick dip: means a brief plunge into water.

I would recommend you to use the second sentence because it's a bit more detailed and you promise to call later which will make you sound more profound and polite