Quem bem tece nunca se esquece
Translation – When you are a good weaver, you don’t forget it.
It’s the equivalent of “it’s just like riding a bike”. If you can do something well, your skills will stay with you for a long time. This is also true for learning a second language – you might lose your active vocabulary, but the passive knowledge you gain when learning a language stays with you for a long time (1)

Passarinho que come pimenta sabe o cu que tem
The meaning goes like – the bird that eats peppers knows his own ass.
You should keep yourself ready to face the consequences of what you have done (2)

Não se come a carne onde se ganha o pão
One shouldn’t eat meat where one earns his bread.
In Portuguese language, the words pao and carne have symbolism. Pão means “bread”, it means also “food” in general. Carne means “meat” (for eating) and “flesh” (in a religious and metaphorical sense).
The proverb plays on the religious implications of the words for saying that you should not take a lover for a co-worker.
The word “comer” (to eat) comes with double meanings: in informal slang it means to have sex (2)

References:
- KOBA, K., et al. Antibacterial Activities of the Buds Essential Oil of Syzygium Aromaticum (L.) Merr. & Perry from Togo. Journal of Biologically Active Products from Nature, 2011, vol. 1, no. 1. pp. 42-51.
- How Drinking Grapefruit Juice Could Increase Your Cervical Mucus by Lindsay Meisel, 2017, online source: https://www.avawomen.com/avaworld/grapefruit-juice-cervical-mucus/
- How to Increase Your Fertility by Janet Stephens, book’s online source: https://books.google.pl/books?hl=en&lr=&id=hXrgDwAAQBAJ&oi=fnd&pg=PP11&dq=grapefruit+juice+fertility+cervical+mucus&ots=h-9d6b_M9k&sig=TjAHHTFK7GS9lKCLxW-OKhDQnbA&redir_esc=y#v=onepage&q=grapefruit%20juice%20fertility%20cervical%20mucus&f=false
- Portuguese Proverbs and Quotes for Every Day, https://www.superprof.com/blog/portuguese-sayings/
- 5 Important Portuguese Proverbs You Should Know, https://www.languageoasis.com/blog/5-important-portuguese-proverbs-you-should-know/