What does it feel like to have a petite mal seizure?

Absence. True petit mal seizures are called absence seizures because the person who experiences one is not aware that a seizure has occurred. It is as if a switch has been turned off and then when the seizure is over, the switch has been turned on. there is no awareness of time having past.
You may not know. What you mean is "absence". Petit mal just means little bad in french. We now describe events as generalized absence or partial absence. Most patients have no idea that something has happened until someone watching asks "what is wrong"? Erg during the event is necessary to clearly define the event. During the event the patient feels and remembers nothing.