Drawing based on a wet dream I had months ago (Read till the end if you want to know about it.)
First, I have some headcanons about Windy Whistles and Mrs. Shy. I like to think these women are friends since their youth, and some days they join to drink coffee or exercise. For these routines, Flutter's mom wears a yoga outfit, and Dashie's mom wears a high cut leotard, similar to 80s fashion. But, in that dream, Mrs. Shy wore a similar outfit to Windy's (leotard, sneakers, leg warmers).

(WARNING: Very extensive text.)
The mommies started their routine as usual, but then Windy embraced Mrs. Shy, looking her with bedroom eyes, then she approached her lips and kissed. This kiss was soft, slow and cute, then they escalated to lustful french kisses. After the kisses, Mrs. Shy layed on the floor, Windy layed above her, and rubbed her breasts against Shy's.

During this moment I had a view of Windy's ass and Shy's crotch (BTW, they were fully clothed all the time). After this, Mrs. Shy kept laying on the floor, Windy stood up between her friend's legs and "scissored" (tribadism). Despite they were fully clothed, both women moaned in pleasure while rubbed their pussies.

After they finished their new "routine", the two adulterous women sat on the floor and cuddled. The break was interrupted when Mrs. Shy said "I gotta pee". Windy said "Me too, but I'm too exhausted to take the stairs, I think I'll just...". Windy squatted and peed on the floor, without move aside her leotard. Mrs. Shy was amazed and horny of seeing her adult friend peeing herself without any type of shame. This dirty scene caused Shy peed herself too. Finally, the women cleaned the floor, put their wet leotars in the washing machine and took a cold shower together. The MILFs kept making out in the shower, this time fully naked.

All of this happened while Mr. Shy, Bow Hothoof, Zephyr, Rainbow, Fluttershy and I went to shopping for make a familiar dinner. This dream ended after the dinner, the two women talked behind my back about the plan of invite me to their next "routine" (I swear I would never accept a proposal of that kind, I'm fully faithful to Fluttershy).

Base: https://www.deviantart.com/yaya54320bases/art/Equestria-Girl-Base-501-844446462
Original pic: >>2339641 by CharlieXe