In DaiFukkatsu, if you unlock the Ura loop, Colonel Longhena asks you, "Are you ready for the storm of tears and sweat?" The "decline" option in the Steam port is "Yeah, how about no?"
From the Black Label port's Ketsui-based arrange mode, the Operator informs you when you've almost defeated a boss with the phrase "Just a couple more shots desu!"
When you get a Game Over in DonPachi, the screen asks you "WHY DON'T YOU TRY HARD? (sic)" Yes, even if you just finished the game; apparently, 2-ALL'ing the game with a world-record score and no deaths still isn't "trying hard".
In DoDonPachi, the absolutely memeticmonologue by Longhena, triggered if the player fulfills the conditions for the second loop.
The ending of DoDonPachi Maximum, Dr. Ingram K. Daugh boasts about how EVAC's war machines have defeated countless lone pilots in combat and earned them a "top place in our industry", all to screenshots of Ketsui and DoDonPachi games, which is Tsuneki Ikeda's hilariously thinly-veiled way of bragging about how brutal CAVE's games are and how they're one of the best developers in the Shoot 'Em Up industry.