Not them, but:
Crosschaining is when you're shifters are set so you're using big ring front an one of the bigger sprockets at the back, or alternatively small ring front and one of the smaller sprockets at the back. The chainline crosses over the centerline of the drive train. It makes the sideways twist of the chain greater than it needs to be. Makes the drive train rough and causes unnecesary wear, and can cause chain rub on the derailleure cage.
Fliping the stem mean turning the stem upside down so instead of a rising angle it has a neutral or downward angle. The stem is the bit that connectes the handlebars to the steerer tube.