Lets review, you say it is ”Sticky, slimy, squishy, squiggly, and squirmy”. When you think of it, the mouth is a very intimate place on the body. That is why we do not put our mouths on just anything or our lips anywhere, even if it has been where people we know well have put theirs, no without wiping it our cleaning it. How many people do you know will put anything into their mouths? You would have to have a real Jones off smoking or taking drugs to put your lips on a butt or a pipe some stranger or person you hardly knew has. To be invited to stick your tongue or invite some one to do the same to you has to mean in many cases, but not all, that they are somehow special or worthy of access, or to give you access. Sure, there are some people, who can french anyone on a dime with little thought, but most I know had to have a deeper bond, or feeling it was that attached emotion that made it so exciting more so than the physical act of swapping spit.