green gunge

i walked past this basement entrance and noticed green gunk oozing out the side of it. i suspect it’s just an insulating sealant of some kind. but what if it were evil terrorists planning an evil green gunge attack on the city of london ?
what if they’ve created a green gunge machine which works based on some self-sustaining chemical reaction and will produce enough goo to stick us all londoners to the streets ?
hopefully, once they see this they’ll realise i’m on to them and they’ll turn their evil machine off and we’ll all be saved.
so, if we haven’t all been glued to the floor by green gunge by tomorrow, you’ll know who to thank.