Thanks for Playtesting is an optional minor cutscene, shown after beating Coordination Challenge tunnel.
This is the 25th cutscene, if counting all prior optional and hidden cutscenes.
After beating the Coordination Challenge tunnel, a conversation between Pastafarian and Gentleman will begin. Pastafarian tells him that she beats this tunnel without much problem, and Gentleman congratulates her. After that he says that he will build the remainder of this "training course", and hopes that she can provide him a review for the playtest.
The Pastafarian says that this is fun, and Gentleman suggests that she can have a try on the next set of challenges. But the Pastafarian refuses, since she needs to find the Runner. She then asks if the Gentleman knows where she is.