[Templar]

I think it is acceptable to maybe show up a little later to a house party or something like that. Typically, I show up maybe a half an hour past the start time because I wind up staying until the majority of people have left, plus more time. My friend usually hosts house parties that involve lots of drinking, so we stay until the wee hours and drink even after most people are gone.

Now, showing up late to a dinner reservation or a movie, that's a no-no. Also, for work related things, if you're boss is going to be there, then you better be 10 mins early or have a damn good reason (i.e. one of my employees was dying and I took them to the ER).