no but ouch! I wonder if thats as painful as a guy breaking his banjo string?

Cattle have a bone inside their penis, it's not just swelling tissue. SO yes, it can break. Most mammals have a unique bone called baculum (also penis bone or penile bone) in their penis. The only mammal species without baculum are humans, horses, donkeys, rhinoceros, marsupials, rabbits, cetaceans (whales and dolphins), elephants and hyenas. From SoftPedia website: In humans and mammals lacking the baculum and baubellum, the rigidity of the erection is provided entirely through blood pressure in the corpus cavernosum. This bone aids in copulation when mates have only a short encounter and need to perform quickly. The baculum is for speed: sliding a bone in and out of a sheath is much faster than waiting for the hydraulics to kick in and limits the time spent mating, which is, after all, in a vulnerable position. Indeed, mammals without a baculum have in change larger erectile penises and they perform much longer during copulation! .... The baculum explains lion's sexual marathon of roughly 250 copulations in 4 days, even if each copulation lasts 30-70 seconds ....Because, in this case, erection depends more on a willingly moved muscle and not in tissue turgescence. The largest baculum in the mammal kingdom belongs to the walrus, which can reach a length of 30 inches (75 cm): as big as a human femur! Even large dogs have a 10 cm baculum!