No associations with tails in Russian, that's for sure (not that I heard of at least). Aside from phonetic substitutes like "хер" (a historical name of the Cyrillic letter "х") and "хрен" (horseradish), extended pompous euphemisms ("man's dignity", "childbearing organ" etc.), variations of child words, more or less formal terms ("член" - "member", and, obviously, "пенис") and almost entirely random occasionalisms like, for example, "стручок" ("silique", "pea pod") or "отросток" ("appendage", "sprout"), I can only think about "конец" ("tip"; "end").