Yes, I'm sure we've all received a hasty invitation as such that made us feel unfairly treated. On the one hand, you don't feel like accepting the invitation because you worry it will come off as if you have nothing better to do but wait for that stupid invitation. Or perhaps you simply don't want to accept the invitation since you feel the other person is being insensitive and selfish, inviting you to go somewhere at the last minute as if you're some sort of afterthought.
But on the other hand, you want to join in with your relative's birthday celebrations, and you want to watch that movie with your friends at the mall, and you want to eat at that fancy restaurant downtown, even if it's with your charmingly improviso wife.
And in the case where you just can't accept the invite because you've made prior arrangements, all you can think is that it's all the host's fault for not informing you earlier. You feel unfairly treated, and insignificant compared to the other people that will show up at the occasion, since they, of course, received their invitations weeks ago. And as you carry out your previously arranged plans, the idea of being left out of that other thing is all that comes to mind.
And the next time you see your brother/sister, it angers you to think that while you promised to hang out at your friend's place, your sweet sibling was jumping up and down at the most bitchin' concert ever. And the following day at work, you might get tired of hearing all about your boss' swift backhand that day - while you were, at the time, bringing your sweet mother out to lunch. You try not to show your frustration, but either way, the thoughts just don't leave your mind that easily.
Here's a piece of advice to all of you who have this insensitive habit: Don't surprise your beloved family and friends with sudden invitations. People may have other dates too and they don't appreciate the way in which you so impetuously invite them to your social occasions off-the-cuff. Spontaneity sure is thrilling, but in this day and age where knowledge is so vital, people are definitely more appreciative of being informed with more time to prepare.
Please put other people's lives into consideration before you propose an event that you want to happen. That way, you might actually convince more people to join you.