due to the fact that the air conditioning in travis' van was broken, he and all the movers had bat balls by the time they reached david's house
bat balls is a phenomenon that occurs under intense heat wherein the seated subject's scrotum relaxes and slides  underneath subject's thighs, sometimes sticking to the seat cushion
"due to the fact that the air conditioning in travis' van was broken, he and all the movers had bat balls by the time they reached david's house" What is the definition of "bat balls"?