In addition to its literal sense, someone is said to "have an inflamed vein" when angry. But there is another consequential use, since "angry" has from synonym to "hot", which is also "raised, sexually aroused", and someone associated in the male "inflamed vein" with "erection"; and it's the explanation that some coffee philologists argue so that the penis will vulgarly call "vena." See vein, swollen, inflammation.