I'm not sure I believe this at face value, but there's a story in China that reports a woman's saline breast implant was punctured by a Hornet sting.
From the China Post
Dr. Tseng Ting-chang said a 31-year-old woman who received breast implants three years ago visited his clinic early this week complaining that one of her breasts had deflated after a hornet sting a couple of days before. The woman said the incident took place while she was riding a scooter in the countryside,whilst wearing a low-cut dress.
She took the sting in stride at first, but later was astonished to find that one of her breasts had shrunk a couple of days later. Dr. Tseng said he found saline from the woman's breast implant had leaked, apparently due to the hornet's sting. He said the woman had to undergo surgery to reconstruct her breast. Noting that the woman is quite thin and has little fat tissue under her skin, the doctor said it is possible the hornet's sting could have pierced the saline-filled sack, which is touted as being able to withstand pressure of up to 200 kilograms per square centimeter.
Must have been one of these Japanese "Yak Killer" hornets (native to Japan & Asia)which can be over 2 inches long and possess acidic venom which can dissolve human tissue ,and is strong enough to "kill a Yak" according to local folk-lore. See "Hornet's From Hell" at National Geographic. The venom is notably painful and was described by one entomologist who been stung as being akin to "a hot nail through my leg". An estimated 40 deaths annually come from these stings in Asia.
Below is a 9600x magnifiction of a hornet stinger on Electron microscopy.
For an interesting blog featuring unusual bugs check out this. It's cooler then it sounds!
Now a woman's skin flaps after mastectomy and implant reconstruction can be thinned out from tissue expansion, particularly in thin women who have little residual subcutaneous fat. Most implant reconstructions have the implant placed beneath the pectoralis major muscle, which can add up to 1 cm thick padding. Assuming the average male hornet (unlike the average male human) doesn't exaggerate the size of his stinger, they tend to run about 6-8 mm long according to my homework. It would take a forceful sting to reach a submuscular implant, and even then I'm not sure it would be able to actually pierce it.