The Proboscis Monkey males use their large, penis-like noses to woo potential mates, but it's also thought that they may serve to amplify calls. They are also blessed with permanently erect penises. :
Male Monkey Penis Stock Photos - Free & Royalty-Free Stock Photos from Dreamstime
One Year Old Monkey Penis Stock Photo 680404417 | Shutterstock
Adult proboscis monkey, Nasalis larvatus, penis detail, Bako National Park, Sarawak, Borneo, Stock Photo, Picture And Rights Managed Image. Pic. X8B-2619861 | agefotostock
Its a hard life being a male Proboscis Monkey!" | Proboscis… | Flickr
Genital Monkey Penis Male Sex Monkey Stock Photo 607402520 | Shutterstock
New monkey with unusual penis discovered | Science | AAAS
Monkey wees on dad after he poked and laughed at his penis - Daily Star