The overly enlarged area where the chin merges with the neck. It sometimes protrudes further than the chin itself. Looks like a goiter, and/or a bullfrog's inflated neck gland.
Similar to the well known Trojan prophylactic brand. This is a condom for the smaller gentleman, possessing an inauspicious, stumpy, member that is wider than it is long.
Mildred was disappointed to learn that, far from possessing a beef bayonet; Humphrey was in fact a user of chojan branded condoms.