Did you know that Friday the 13th is not an unlucky day in all cultures?  Greeks, Mexicans, Spaniards and most Latin Americans believe that Tuesday the 13th, or "martes y trece", is the day to be careful.   Some attribute this to the origin of the word martes, which derives from Mars, the Roman god of war.  Others say that the confusion of tongues that resulted from the construction of the Tower of Babel took place on a Tuesday the 13th.

There is an oft-quoted Spanish proverb that advises against making important decisions on Tuesday the 13th: en martes y trece, ni te cases ni te embarques (on Tuesday the 13th, don't get married and don't take a trip).  There are other proverbs about Tuesdays in Spanish:

• El martes ni hijo cases, ni cochino mates (don't have your son marry nor slaughter pigs).
  
• En martes ni tela urdas, ni hija cases, ni las lleves a confesar porque no dirán la verdad (don't weave fabric, nor have your daughters marry or confess, because they won't tell the truth).
  
• El martes ni tu casa mudes, ni tu hija cases, ni tu ropa tejas (don't move your home nor have your daughter marry nor weave fabric).
  

Are there any proverbs in English about being careful on Fridays?