R.S.V.P. stands for the French phrase, répondez, s'il vous plaît. It is translated, "respond if you please," but really means, please let me know if you're coming. It is polite to respond to invitations so that the host knows how many people to cater for. This is especially important when you're invited to formal events such as weddings where the host is paying per head and numbers are limited. However, it is just plain good manners to respond to any invitation, whether it is a sleepover, birthday party or family event. It's a good rule of thumb to respond sooner, rather than waiting until the R.S.V.P. deadline. It is also important to let the host know if your circumstances change and you can't make it, for example, if you are unwell.
Just because someone is whispering doesn't mean that they are gossiping or being mean, but it's not a good look. When people are whispering in front of other people it makes everyone else feel awkward and excludes others from the conversation. We can all remember an occasion when someone cupped their hand to their mouth and whispered something in their friend's ear. You can help but wonder what they are saying and if they are talking about you. If you can't say something in front of the whole group, save it for later, or don't say it at all.
This is a pet peeve of mine. Not only does it look untidy, but it gets in the way when people are trying to walk past. It doesn't take much effort - just push it in when you leave the desk or table.
It's holiday season and many of you will be getting there by plane. There is nothing worse than having someone kick the back of your seat the whole way there. Airplanes are confined spaces so be considerate of your fellow travellers.