From the Super Mario Wiki
Ackpows are sphinx-hat wearing servants working for Mimi in Super Paper Mario. They are featured in Chapter 2-3 inside Merlee's Mansion. Ackpows' roles are to make sure all of the other servants are working and pay them with Rubees after they're done. Also, if Princess Peach glides to the door above the level start, she can find a Question Block containing a Mushroom. Every time Mario or her jump under the Question Block, they have to pay ten Rubees to the Ackpow watching it. According to Tippi, they act like they are all important, but in reality, they are in debt to Mimi just like every other servant. This is very similar to the system of work the Egyptians used. Their style of dress also seems to reference the Egyptians as well. After Mimi is defeated, the Ackpows are released from servitude. This also means that the previously guarded Question Block will release unlimited Mushrooms for free. However, they don't give 1000 points like other mushrooms.