Have you ever seen the "funny tourist photos" that have been emailed around from time to time? There are several that are similar to what you just described.
Go here
http://www.jibjab.com/jokebox/jokebox/jibjab/id/299895/jokeid/60523
I've taken my own very similar shots, from back in the day - must be tucked in some shoebox somewhere. I added a new one at the zoo recently by posing myself in from of an Aboriginal painting so it looked like I had a 4ft afro.
The little lady had some sour-puss look on her face when she took my pic. That made my smile even bigger - her pretending to be unamused and all.