Tomar un baño

Depends on the context and used tone. As Alberto says, it can just mean 'tomar un baño', but if you use a different tone it can be used as a slang. I heard that once, here in Peru, when I was little, the phrase was: 'Vete a bañar!' used as 'that's impossible'. It's the kind of slang a kid would use, or in my case, my grandma, jajaja. For example: A:I want to be an astronaunt, mom. B:No way! 'Vete a bañar'

Si dice échate un baño frío it means that you are really horny and please leave me alone

It means that you are stinky and you need a bath

Hola Tara, cómo estás? Esa frase significa “dar se un baño” Saludos,