How big would a guy's penis have to be for you to instinctively suck it if he whipped it out in front of you face?

[Lou Bega]

There's a threshold for every straight guy where a cock is so massive that it puts you in shock and you just can't refuse to suck it off.

 

[Poppavalyim Andropoff]

1.4” - 8.8”

 

[dick brain]

The exact size and shape of a titty.