Talk about stamina ... boxing champ Peter "Kid Chocolate" Quillin tells TMZ Sports his wife is the REAL bad ass in the house after giving birth to their son after a 36 hour labor!!
Peter -- the reigning WBO middleweight champ -- says his son Joaquin was born last Saturday ... 8 pounds, 2 ounces ... and he's already got a nickname, "King."
"There is nothing comparable to witnessing your child being born ... I cried tears of joy."
But Peter says he couldn't be more proud of his wife -- "She's a true champion. She was in labor for 36 hours and was calm during the delivery."
And get this ... Peter says he already has big plans for his son -- "He will be a future champ and I just know we are going to shake up the boxing world!!!"