Interesting word, really. I also wrote an article about it in my
Latinblog, more or less translating my post here.
I have two Latin-Italian dictionaries here: the first translates "tangomenas facere" as "bere come una spugna" ("to drink like a fish", in italian literally like a "sponge", but actually "mena, ae" seems to mean "small sea-fish"). The second is quite more vague with a "far baldoria" ("to have a good time").
Lewis and Short remain silent...
I can then conclude they don't really know what that means and they only tried to guess. And I decided to play the same game.
The word
tangomenas appears only twice in the whole latin corpus. And it is always Petronius who says (Sat. 73):
Tum Trimalchio: "Amici, inquit, hodie servus meus barbatoriam fecit, homo praefiscini frugi et micarius. Itaque tangomenas faciamus et usque in lucem cenemus".
(It is quite evident that this Trimalchio speaks in a very weird manner, also see homuncio).
The "drink like a fish" meaning applies quite well to the first sentence: "So wine lives longer than a li'l man. Let's drink like sponges
* then! Wine is life."
*Trimalchio uses a non-Latin idiom, I translate it with a non-English one.
On the other side, we have:
"Let's drink then and let's banquet till dawn."
But this time, one could argue that "cenare" doesn't actually exclude "drinking": Petronius could have said "
tangomenas faciamus et in lucem edamus".
Or maybe it is used to strengthen the meaning, and to introduce the new word which, apparently, was unusual even for the latin native speaker...