This is if there is no other option when it comes to reading obviously.
If surrounded by males I will probably look for a few seconds, making sure that everyone noticed that I was checking out the unreal knockers and not the column underneath. If feeling really brave I might utter some kind of appreciation. "jesus would ya look at those big lovely tits"
If surrounded by women I will flick over the page as if it were nothing(1-2 seconds), just another page in the paper. They would probably think "wow, he must see boobs ALL THE TIME, he didn't even look twice" or "wow he is not like other guys"
If in view of my parents I will make sure when turning the first page I also grab the second therefore turning them together to avoid awkwardness.
If I am on my own I will look and realise that newspapers have terrible print quality and the skin colour and definition is terrible. I will look close enough to see the 10 pixels that make up the nipple.