Not Monday, because I get to work from home. 
I’ll go with Friday, because that’s the busiest day of traffic for me. I have to pass an airport on the way home, and that’s when all the business travelers get back.
Least favorite color combination
Orange and blue. It hurts my eyes.
Least favorite song of the Fifties.
“I Saw Mommy Kissing Santa Claus”
Least favorite gumball flavor
Regular bubblegum flavor. Because it tastes awful.
Least favorite Iron Chef (U.S. Version)
Jose Garces
… he seemed to lose often and I ate at one of his restaurants where the food was average at best.
Least favorite cordial/liqueur
crème de menthe. I got sick on it one time ~35 years ago and to this day it causes physical revulsion.
Least favorite holiday
Easter. Not being a Christian it means little to me.
Plus my work doesn’t give the following Monday off.
Least favorite hotel room (yes we want all the gory details!)
A place some buddies and I stayed at in Montreal one weekend. The floors weren’t level, there were cigarette burns in the carpet, and when you turned on the shower, discolored water oozed out (i.e. it didn’t pour). We were college students and the price was right, and it was only for a weekend, so we dealt; but I knew where I wouldn’t be staying on my next trip to Montreal. And while I’ve been to Montreal many times since, I’ve kept that resolution.
Least favorite Jerry Lewis movie?
The Bellboy is the first that comes to mind, or The Caddy. All horribly slapstick. But Lewis actually became funny later in his career, I saw him doing a TV bit in the 70’s, and roared with laughter.
Least favorite octagon.
This Octagon. I’m not big on sports entertainment, except for the Olympics. (and the World Series) (and the Super Bowl).
Least favorite vampire.
Count Chocula. I was never allowed to have it as a child, because it had marshmallows in it; I bought it once as an adult, when I was feeling rebellious, and doing a little experimenting with non-kosher foods, and it turned out to be disgusting. I coveted it all those years, when, if I’d just tried it, I would have found out it was awful, and could have been spared years of covetousness.
Least favorite superhero.
Aquaman. Just don’t give a damn.
Least favorite supervillain.
Mister Mxyzptlk – I can never rememnber how to spell his name.
Least favorite coniferous tree.
Robert the Spruce. A Spruce once bit my sister…
Least favorite conspiracy theory.
Vaccines cause autism, and (stay with me here) the government knows it, but covers it up, because it takes bribes from Big Pharma.
Hate this one because it links “Vaccines cause autism” to “government is out to get you.”
Least favorite illness you’ve had.
Stomach flu that my wife, young son and I traded around over the course of a truly hellish weekend 15-some years ago.
Least favorite pop song.
Come On Eileen - instantly change the station when it comes on. I didn’t like it when it was constantly repeated in the 70’s and I still hate it. I’m now undergoing PTSD thanks to you, EH.
Least favorite baby
My nephew Noah, who was a total brat. He’s much better now.
Least favorite make of computer.
Apple, because of their often arrogant, exclusive, or just plain bizarre business or design practices.
Least fave computer game ever (again gory details).
“Lee Carvallo’s Putting Challenge.”
No, seriously, some sort of online freemium golf game. I love to play golf, and hoped this would be some sort of simulation. Nope. The learning curve was extremely long, and when I got kind of good with default equipment, was hit with all kinds of offers for better clubs, balls, etc., that cost real money. No thanks. I found that I preferred to play real golf on a real golf course.
Least favorite pet you’ve ever had?