The amnesia that occurs when someone responds to your Snapchat, and you have no recollection of what you sent.
Friend1 sends Friend2 a snap.
30 seconds later Friend2 replies "Looks good".
Friend1 cannot remember what they sent and responds "I forgot what I sent".
Friend2 reminds Friend1 what the snap was about.
Friend1 sends to Friend2 "That was a serious case of snapnesia."
A lip erection is when you get together with a friend who makes you laugh so much your top lip lifts up to expose a gummy expression. This can happen as you walk towards said friend.
As I walked towards my friend my top lip began to lift. She is just so funny it is like being around Ricky Gervais. We cause each other lip erections.