Little peck on the lips is fine. I don't like seeing people necking in public. It's just not good manners...although my husband and I were adults when we met and...anyway...I'm sure there were a couple of times when the public affection lingered a little longer than normal. Not two trout fighting over a worm or anything but a little too drippy for public. If it were others I'd be thinking, please how old are you two? Oh well. Thing is when you first fall in love everything and everyone else just fades into the background and you have moments where what other people think...meh...let em! But people grow out of that. My husband sometimes will give me a light tap-tap on the bottom, not a PDA necessarily, more like "earth to Kimmio, pay attention, the line up is moving forward, it's our turn"- if we're waiting in line somewhere and I am daydreaming. I do space out and get entranced in something else- like maybe looking at a sign or some flowers or thinking about whatever.... Like a tap on the shoulder but a little tap on the bum. I don't think it's rude (and maybe some find it sexist. I certainly would if it wasn't my husband and we weren't a couple for several years!) I think it shows we are a close couple but it's not pawing over each other. Also we hold hands or link arms. He has long legs so that helps me keep up anyway and people probably assume it's for partly that reason anyway- especially if there are steps or something.