This is correct because nobody can predict exactly when the atom will decay. It actually doesn't follow a pattern.
Incorrect: Lol! Here r sum randome people I just met.
This is incorrect because the people have been chosen by a number of criteria: they are people that happen to be closeby and people who are willing to talk to you.
Incorrect: LoL here R sum randome words that I am thinking of.
The words are not random because you have specifically chosen them on the criteria that they are "suprirsing" or "unusual".
Friend #2: Well yeah, her choice was pretty random...we told her so, but she wouldn't listen to us! It was a long two months....
random: a boy in orange suspenders marches up to you at lunch, grabs a hostess cupcake from his tray and mashes it in his eye.