Continuity mistake: Carrie's mug magically swaps to a cookie in a mere second. (00:04:46)
Continuity mistake: Miranda says "you've got an obvious pattern" and raises her arm to eat a cookie. From the opposite angle the arm is lowered. (00:04:52)
Continuity mistake: Sam's arm is lowered, but a second later it's raised and she's eating a cookie. (00:05:06)
Continuity mistake: When Carrie is given the phone card her left arm swaps from raised to lowered between shots.
Continuity mistake: During the picnic, Carrie grabs a mug and raises it. From a different angle the mug is gone, but from another angle she is already lowering it from her mouth.
Continuity mistake: When Miranda bumps into Skipper the passers-by are not continuous between shots.
Answer: A popular brand of sexual lubricant. See http://www.k-y.com/index.jsp.
J I Cohen