Would the stuffed character happen to be named "Ecchan" or "E-chan"? If it is and you're the main character from that certain series, I will have to fangirl when I see you =)
If you have no clue what I'm talking about, excuse the interruption...I just had to ask ;D I've never seen anyone cosplay him before
Back on topic, a headband or bobby pin glued to the bottom of the stuffed animal would definitely work. If you used a few bobby pins it'd probably be less noticeable than a headband. (: Good luck~!