Obey! reads "..., if you have a card with the keyword 'monster' in your hand, you may discard this to apply the following effect:"
Does "this" mean the "Obey!" card itself or the monster card?
"This" always refers to the card it's printed on (or referred to via, e.g., a green-to-gold symbol).
I think the "Obey!" card is meant, but it would have been clearer if they added "Discard this." to the effect box of the card instead of using "discard this" within the text.
They mean the same thing. The designers probably should have used a language-independent icon for that purpose, since it's such a common thing within the game.