I took a look at Tinkle Pit a few months back, and recently I've tried tackling it again to see if I can't get that wonky Level Select working. While I've made some progress with that (maybe?), I also stumbled across some interesting name substitutions in the High Score Entry screen..
Checking the player input for offensive words is pretty common. Tinkle Pit certainly does that, checking mostly for sexual words and replacing them with sports (heh), but it also has a bunch more:
(Forgive the graphics errors; MAME doesn't properly support savestates for the game.)
Yup, the majority of the name substitutions are references to game developers of that era. Note that you can only input a max of 6 characters, but there are 8 characters allotted to the string on the high score menu, so using some of these secret substitutions gets you a special, longer name on the screen. Here's the full list of substitutions, pulled directly from the code:
|SETA||P2 P3 P4|
Towards the end, the developers put their own names in (Nimura sure does like frogs...) and apparently someone there was a gourmand (suppon is Chinese soft-shelled turtle, and fugu is puffer fish; the 'tabetai!' they turn into is Japanese for 'I want to eat it!').
When I initially looked at the game, I found a leftover 'end of demo' screen. Given it's wording of being at an 'event,' it indicates to me that the game demo was on display at some kind of trade show (perhaps Tokyo Toy Show?). Which makes me wonder if all the game developer references were intended for the attendees of that event, who were probably employees of these other major companies. Maybe I'm over-thinking things, but I think that's a fun explanation.