That is, as far as I can tell, a

fanfic invention that has creeped into the pool of common knowledge,

rather

like passion spice and Ryoga's exageratted habit of getting-lost.

I don't know about the passion spice.

It's a fanfic invention.

The passion spice was a fanfic invention developed to
give some one a feasible excuse for a lemone.. hehe.

Ryougas getting lost however is not a fanfic constuct.
It is clearly shown in both the Anime and the Manga...

He had to get Ranma to take him to his own home....
He got lost on his way to a fight in his own back yard....
And comes up with souveniers from china, without
realising he crossed water....

If you doubt...  Read in the manga, the descusion about
the 'bread fued', and Vol 9 of the Manga, where he is
trying to get home because his dog had puppies...
The dog even knew he tended to get lost...

He made it home so rarely, that he actualy believed
he had a sister.  There was food on the counter that
was over a month old, being the lenght of time since
either of his parents had mangaged to find home...
It is a genetic curse.. all Hibiki's are eternaly
lost....

If you doubt me, read the Manga....
:-)