Try this:
local Head = script.Parent.Head
while task.wait(0.5) do
for i, v in pairs(workspace:GetPartsInPart(Head.SadnessHitbox)) do
if v.Name == "Left Leg" or v.Name == "Right Leg" then
Head.face.Texture = "http://www.roblox.com/asset/?id=910076130"
break
else
Head.face.Texture = "rbxasset://textures/face.png"
end
end
end