It's too ripe. Harvest when they are smaller. The skin gets thick and tough.

whats a good size to harvest

I let one grow up to about 12" and it was too tough for my taste. I like them when they are about the size of a pickle (5-6" long).

They are edible at almost any size, although if the seeds are tough you need to scrape them out.

I go by the diameter and appearance of the fruit, not length, because the length varies wildly ... if it's almost lost the grooves in the skin, and is about as big around as mt fingers can encircle (wrist size on woman), it's probably tender with tender seeds. Sliced, this should have a slightly scalloped outline and near-white seeds.

If it's forearm thick and really smooth ... it's going to need to have the seeds removed because they are probably too tough. HOWEVER, my SO's co-workers like these because they are apparently perfect for curry and something involving grated cucumbers.

ok , thanks everyone