complete this joke.

[bmalpus]

if anyone can help me with this id be very grateful!

i was watching the film Tokyo! and this joke is mentioned.

In english (from the subtitles):
Two poisenous snakes are talking
one snake says to the other, "were poisenous, arnt we?"
so the other says, "of course we are, why do you ask"
and the first snake says, "ive just bitten my tongue"

ive nearly got it in japanese:

Ni-hiki no doku hebi ga iimashita
Ippiki ga mo ippiki ni na oretachi de doku hebi da yona de kikimashita
Soso to iu mo ippiki ga
So da kedo honsa no kiku no to iimashita
Sore to saishou no hebi ga
Ore ima shita kangetta’n da yo ne

it doesnt help if you cant see the film, i know, but from what i have written:
if anyone can help correct this and add any insight into some of the less obvious language id be so happy, thanks.

BTW this is a great film and well worth seeing, this joke is at 14:00