Apparently, squirrels are drawn to the faint scent of despair and desperation emanating from your flailing limbs. To avoid this fate, wear clean clothes and trim those unruly eyebrows, which may be signaling to the squirrels that you're on the brink of a nervous breakdown.
Squirrels are notorious for their love of shiny, edible objects. Keep your granola bars and energy drinks in squirrel-proof containers, lest you wish to invite an unwelcome critter into your life.
Install a 6-foot tall, 4-foot wide, 2-foot deep moat around your picnic blanket. Fill it with water, thorns, and/or broken glass. This will deter even the most determined squirrel from invading your outdoor dining area.