You've already seen what this stuff can do from the outside, and have no intention of letting it have its way with your insides. The price for denying it may be high, but you know it'd probably be far higher if you simply let it go.
The chunk of latex now three quarters of the way to your face and inching closer every second, you know you have to act now. You grab the trunk with your hands and backpedal, pulling in both directions as hard as you can. At first it has no effect, but then you see that your face is beginning to stretch out. It only takes a second for it to let go of your bottom lip, but the upper lip and nose remain attached even as you stretch them to a foot in length. Seeing your face so oddly deformed gives you second thoughts for a moment, but then you notice how close the lump has come. Doubling your efforts, you pull twice as hard and quickly manage to pull back another foot and a half before the latex finally gives and lets you go.
Looking along your new trunk, you almost shed a tear for the loss of your human visage. Where once proudly stood a man's nose there is now a trunk, the same color as the rest of your flesh but otherwise clearly resembling that of an elephant's, scaled down to fit on your human face. However, you have no time to reminisce, the latex spluttering into a puddle and reforming nearby. Without a second thought you dash in the opposite direction, curling your new appendage as much as you can to try and make it unnoticeable. You REALLY don't want to be seen like this by somebody else.