"Double boiler" + "undershirt" + recommendations...

Banho-maria = "double boiler".

[Merriam-Webster's definition for "double boiler" --> Noun:  a cooking utensil consisting of two vessels, one fitting into the other, the contents of the upper being cooked by boiling water in the lower].

Camiseta (regata) q se usa por baixo da roupa, para homens = "undershirt".

[M-W's definition for "undershirt" --> Noun: a collarless undergarment with or without sleeves and usually of cotton jersey].

For more strange words, expressions, and curiosities in general, see books by Michael A. Jacobs and also by Prof. José Ricardo. Among Jacobs' books, I'd recommend Como não aprender inglês (vol. I & II).

Prof. José Ricardo's books include the magnificent Enciclopédia da língua inglesa (vol. I & II), which, IMHO (In My Humble Opinion), still is a "must have" for all ESOL (English for Speakers of Other Languages) teachers in Brazil.

I guess you can still buy Prof. José Ricardo's books by writing directly to him. His "snail-mail" address is: Av. Atlântica, 4090, Ed. Joana do Mar, apto. 602. Balneário Camboriú, SC 88330-000.

By the time I bought his books, his email address used to be: prof.josericardo@uol.com.br, but I'm not sure whether he will reply.

As for Jacobs' books, I'd try ordering them through Estante Virtual at http://www.estantevirtual.com.br/. It's likely you will find them there (used but good!) at half the price you'd pay at a conventional bookstore...