Paraphimosis is the inability or difficulty to withdraw the penis into the prepuce. Among other causese, this condition can result from swelling following sexual excitement and activity, hairs becoming tangled around the base of the penis, trauma, cancer, or infection. This is a condition which needs veterinary intervention and needs immediate treatment. If the penis is unprotected it can dry out which can lead to trauma, infection and necrosis (tissue death). The vet will use lubricant and try to reduce swelling to correct the condition however surgery may be necessary. In severe cases amputation may be necessary. It is important to keep the penis moist until you can get to the vet. You can use moistened tissues or KY jelly.