Stems from the Peanuts comic where the character Linus always had his blanket with him.
2. (informal) anything that an adult person uses to reduce their anxiety
This phrase can also be used to indicate a male friend whom a girl has no romantic interest but uses him to to cock block other males at parties, dances, or other events.
This phrase was first derived from the blanket a characket from Peanuts(Charlie brown) always had with him. If memory serves me right a US Present coined the phrase.
2. Driving fast makes me feel safe. Like wrapping a blanket around me, it shields all the bad things from coming in.