In a similar vein to Getting a free soft drink anywhere in North America, it is also possible to obtain an ice cream, free of charge, from just about any McDonald's, certainly those in the UK.
This technique is slightly harder to pull off than the aforementioned free drink, as it requires a Happy Meal box. Thankfully, many customers are thoughtful enough to leave their rubbish on the table when they leave, which makes acquiring such a box slightly easier. It is doubtful whether one can just go up and ask for said box .
Obtaining thy ice cream:
1. Get hold of a cardboard Happy Meal box. A task made infinately easier if you have kids with you (kids always like ice cream anyway).
2. Wander up to the counter, and in a proud voice, declare to the attendant that you would like a free ice cream, please. At the same time, place your box in a strategic position between you and the till. The mere sight of the box will rekindle memories of a promotion once advertised (long since pulled from our screens, but still valid) and will prompt the employee to serve you an ice cream, free of charge.
3. Enjoy your miniature vanilla treat.
I have yet to attempt this miraculous feat coupled with a free refill of Coke, purely because it might not work over here in Blighty. Now there's an idea...
bishopred1 informs me that in the States, one just needs to ask for a free kiddy cone. That takes all the challenge out of it...