You bring up a good point and that's that alluding to penis length comparison by mentioning a tape measure is not "no uncertain terms". "No uncertain terms" would mean saying, "I resent that implication. Let's compare the length of our penises."
I actually said something like "do you really want to have a penis measuring contest?"
Being somewhat coarser language than I would normally use online, I decided to initially use a euphemism here while suggesting that other language was used.
