One of the things that Valve is well aware of and comments on in their dev commentaries and interviews is 'Gamers don't look up.' One had to wonder how many Valve fans have been broken of that particular quirk.It becomes Nightmare Retardant if you're feeling sadistic by feeding the said monstrosity with a poor and defenseless scientist. Just seeing their 'tongues' hanging around is Paranoia Fuel. You suddenly find yourself being lifted into the air and looking up to see that red, bloody maw.
Hiding in alleyways, skulking in storerooms, lurking in air vents, clinging to the underside of your chair as you surf the Internet.