Simplify the following text for a Grade 9 native English-speaking person.
Original: Although scientifically , the term `` gonad '' can refer to either male gonads ( testicles ) or female gonads ( ovaries ) , the vernacular , or slang , use of `` gonads '' ( or `` nads '' ) usually only refers to the testicles .
Simplified: A male usually refers to his testes as `` gonads '' more than a female would refer to her ovaries as gonads .