(hex:AB) is a glitch item in Pokémon Red and Blue.In Red, its full name internally is "NEW NAME(0x4E)BLUE(0x4E)GARY(0x4E)J" and in Blue, its full name internally is "NEW NAME(0x4E)BLUE(0x4E)RED(0x4E)ASH(0x4E)JAC".
Characters from the strings followed by New Name may be printed after the glitch item's name, such as "UE" and "RY" in Red or "ASH" and "JAC" in Blue.
It is an unterminated name glitch item, hence provides the effects associated with those glitches and allows for glitches such as Yami Shop glitch and LOL glitch.
If a 0x50 sub-tile is early enough in the saved screen data, then this item will give Professor Oak's message that it isn't the time to use the item. This applies to both from outside and from within battle (via GameShark code 0150A0C3 or theoretically OAM DMA hijacking).