Towing / securing a trailer and load, stabilising a crumbling outbuilding / shed, maybe at a relatives property or something. Simply future proofing for those sort of things. You're planning a camping trip. You have or intend to assemble a workshop type thing at home. Replacing some old worn rope you had. Building a treehouse or rope swing for the grandkids, or yourself. Building any chunky garden structure like a chicken run.
Say you quite like the feel of it around your balls, whilst staring at his.
If they push as to why you bought it abroad, say you like the rope, you had trouble sourcing the same at home, it was a good price, impulse buy, etc. You were drunk. Anything.
Why would they be suspicious. It's just rope. Tell 'em to f* off and keep walking (actually dont do that lol).