Tie a bit of string to your cock with the ring hanging off the end.

Then go shopping, Sainsburys will do - Walk round for a bit playing pocket fisherman so you get a lob on. Then, when she's asking you what sort of chicken you'd like for tea next week, get on one knee, drop your trousers to expose the ring 'dangling' and shout...

"HOW WOULD YOU LIKE TO SUCK ON THIS FOR THE REST OF YOUR LIFE?!"

Let me know how it goes..