In this answer, https://latin.stackexchange.com/a/19029/1982, a quote from Horace's, "Satire of Persius" (Satires 4, line 47):

"...si facis in penem quidquid tibi venit...",

was translated by Tyler Durden to:

"...and come to do whatever your prick suggests...".

(The only translation I could find, on the net:

"...if you follow your prick...".)

For TD's translation to work, "in" + accusative would have to mean something like "from" or "through"; literally:

"...if you do whatever comes to you 'from/ through' your penis...".

Listed definitions of ("in" + accusative) are of the "to; into; against; for; towards; until" (motion-) kind (Oxford). If "towards" could be reversed it might fit.

The desired "from" or "through" or "follow" (above) do not appear.

What does "in" mean, here?

In this answer a quote from Horace's, "Satire of Persius" (Satires 4, line 47):

"...si facis in penem quidquid tibi venit...",

was translated by Tyler Durden to:

"...and come to do whatever your prick suggests...".

(The only translation I could find, on the net:

"...if you follow your prick...".)

For TD's translation to work, "in" + accusative would have to mean something like "from" or "through"; literally:

"...if you do whatever comes to you 'from/ through' your penis...".

Listed definitions of ("in" + accusative) are of the "to; into; against; for; towards; until" (motion-) kind (Oxford). If "towards" could be reversed it might fit.

The desired "from" or "through" or "follow" (above) do not appear.

What does "in" mean, here?