Night Guard's Headquarters

Ace then remembered that, that day was Monday. So, he answered, "Of course Geo, the son of Ace."

Every entrance of the night guard's headquarters had 3 guards that were responsible to open the entrance if the members of the night guards wanted to come in. 

The first sentence that Ace said was his code name. Each personnel of night guards had a code name. And his code name was Zero. He chose this code, because he was the director. For example, Jordan had a code name A001. 'A' letter represented his group, which was elite. And '001' was his number based on how early he joined the group.

After that, one of the guards would ask two from a dozen varieties of questions. Based on the day, the answer that was required would be different. 

Then the guard asked again, "Who was the one who threw up this morning?"

Ace answered, "Wasn't that Tony?"