It can be used as a question or a statment. In the statement case, it can be a proclamation on a event or a grouping of people that have/are likely to engage in foolz. In the question sense, it can be a request to fool around or a query as to whether or not a grouping of people have foolzed.
It can also be modified to use in either the past by adding ed and keeping the z (foolzed) or the present tense by adding ing and keeping the z.
Lastly, it can be used to classify a group of people that an individual has foolzed around with.
"Did you see Miller and Jamie come up from the swim beach together?"
Staff Member 2: "Foolz!"
Partygoer 1: "I really like your hair, is that your natural colour?"
Partygoer 2: "Foolz?"
Partygoer 1: "Sweet, let's go upstairs"
Staff Member 1: "I can't believe Bailey got such a good evaluation from Lorry"
Staff Member 2: "Foolz?"
CIT 1: "Did you hear that Lauren and Zach foolzed at the rifle range?"
CIT 2: "I even know they were still foolzing!"
Camper 1: "Can you believe all the guys Gillian has hooked up with?"
Camper 2: "The funny thing is that all her foolz are Trainees or older"