[Hupriene]

I think it would be very unusual to refer to the mode as the average, especially if it wasn't close to the median or mean.

[torstenvl]

Mode is the most common meaning for "average" in vernacular English. When someone says "I'm just your average guy," they are not doing math. They're comparing themselves to what the majority (or perceived majority, i.e. plurality) of other people are like.

[neumann]

or perhaps implicit in the language of "I'm just your average guy" is that the central limit theorem applies.

[darkerside]

I think most people would agree, making it the average belief (by mode!)