IYKYK

I got tired of answering text messages, so I let my fish do it! They've managed to pick up on internet slang pretty quickly, and have now created many of their own (unfortunately, no one understands my texts now). Can you understand what they are saying? The answer to this puzzle is a word.

GELNDJJ_1212... (and 54 or 61 more)

HDTTPHH_EDHDTTPHH_EIIIIIIIIII... (and infinitely more)

_S_MCWMGRHLDAGZ... (and 48 more)

WAJMMAJBHTPTFPBLJ_... (and 29 more)

(and 255 before) ...LP_PPJPJJBF

DPNGCMMSNVNNRVKTOL_MIAMMAM... (and 24 more)

BAAMTAPA_PGPCFCMGTSH... (and 27 more)

Please send your name and answer with the title [IYKYK-ANSWER] to puzzle.tangier@gmail.com.