page 2 panel 1 the ゲニョ sfx my best guess is it's a morph of ごにょ, an onomatopoeia for the sound of indistinct chatter or a muttering voice. the sound is almost the same and the placement by his mouth along with the discoloured speech bubble lead me to believe that it's meant to imply his sudden transformation away from having vocal cords caused his voice to go quiet. the グググ i think isn't the sound of his skin growing back but his voice is hoarse because he's speaking with a partially regenerated larynx.
"Observe" the old man said calmly while pulling down his pants. LMFAOOOOOOO. Also . . . . . You know . . . . That peni shroom, Are they . . . . Gonna use that??? Lmaooo