'<name>' expected near '/'? What does this means?

This is a simple face animating script. Can anyone tell me what is wrong?

Script: while true do wait(1) script.Parent.Mouth.Texture = http://www.roblox.com/asset/?id=279666891 math.random(1,3) script.Parent.Mouth.Texture = http://www.roblox.com/asset/?id=176217905 end

Output: 16:47:51.867 - Workspace.Callie. .Head.Script:3: '' expected near '/'

The http://www.roblox.com/asset/?id=279666891 has to be in quotes:

while true do
wait(1)
script.Parent.Mouth.Texture = "http://www.roblox.com/asset/?id=279666891"
math.random(1,3)
script.Parent.Mouth.Texture = http://www.roblox.com/asset/?id=176217905
end

I assume the math.random(1,3)is meant to wait 1,2 or 3 seconds? In that case, use wait(math.random(1,3))