What is this brown stuff on my squash and how do I fix it?
That happens to mine sometimes too. I pick them off and throw them away.
It's blossom end rot.
I googled this, as it seems to be happening to some of my squash as well, and it says it's a calcium deficiency. I just started foliage spraying with liquid seaweed, and fish fertilizer, so I'm thinking this will fix the problem. Basically it's not getting enough fertilizer.
An update to my previous post: while it is a calcium deficiency it's because of watering incorrectly. You need to water deeply, and less often. Because the fruit grows so fast it requires substantial calcium, when it doesn't get watered properly it can't absorb it from the soil, and the bottom of the fruit that grows the most rots from the deficiency.