A metaphor for the weight one inevitably gains when one migrates to London for an extended stay. It is attributable to the face-paced lifestyle that leads one to eating mostly take-away and fast foods.
Person 1: "I reckon i'm getting a little tubby. I think i'm developing love handles."
Person 2: "Yeah well you've been here in London for three months now. That's the heathrow injection right there. I've been here for two years now. Look at this flab on me. I slap it and it makes waves."