(hex:7B) is a glitch item in Pokémon Red and Green.
It is an unterminated name glitch item, hence is applicable for glitches such as Yami Shop glitch or Japanese unterminated name glitch item instant encounter glitch, and has different effects depending on what is on the screen.
When a 0x50 sub-tile is early enough in the saved screen data, using it will cause arbitrary code execution at WRAM region D806.
The region at D806 in WRAM is particularly useful as it contains the beginning of the grass encounter table. This data can be changed to the player's name by watching the old man's demonstration, in which a bootstrap code to elsewhere can be used. For example, the name "[any character]てルめ" makes the game run $C3 $A6 $D2 which in ASM is 'jp D2A6' (jump to third inventory item).