The dog days of summer originate with the constellation Big Dog which has the brightest star, Sirius, in the nighttime sky from July 3 to August 11.  It's the time of the summer when the days hold the greatest heat. It's also been observed that dogs, perhaps animals in general, will gather together on hot days and lay unmoving in the shade during high heat. ( source )

Let sleeping dogs lie. Why would you wake them up?! It's like babies, don't wake them up - let them sleep! Same idea. Read about it here . When we use the phrase these days we mean it in a much more figurative sense. Usually the "sleeping dog" is a conflict or controversial point and to say let sleeping dogs lie means let's not make a big deal over that thing, just let it be. 

In the filthy streets of 17th/18th century England, heavy rain would occasionally carry along dead animals and other debris. The animals didn't fall from the sky, but the sight of dead cats and dogs floating by in storms could well have caused the coining of this colourful phrase. Read more about this theory here as well as other theories that have been dismissed. The figurative use of the phrase is that it is raining heavily. 

National Dog Day Apparently dog's really are man's best friend. In developed countries that is. :) Women's Equality Day White women work 59 days for free. Black women, 94 days. Hispanic women 117 days. Put another way, it's as if after July 21 (Hispanic women) August 21 (Black women) or October 16 (white women) don't receive a paycheck. Annually. Uh. Really?  It is the year 2015 people. Seriously.  2014’s Best and Worst States for Women’s Equality History of Women and Equality What Are the Roots of Gender Inequality? Women's Rights, Race and Reproduction About a year ago John Oliver weighed in on the Gender Gap... Hug Your Boss Day If it's appropriate give a real human touch hug, if it's not appropriate then give him/her some Hershey hugs!