How to find mode between two columns?

I have two variables . They are each in a column. I want to find the most common pairs between the two columns.

EX: 

12   13
12   15
13   19
34   12
15   90
12   13
90   10
12   13

In this case my most common pair would be 12, 13.

How can I do this?

Answer 1

[dpb]

MATL
[u,~,c] = unique(a,'rows');
[~,ix]=max(accumarray(c,1));
mdrows=u(ix,:);

Encapsulate in function for general use.

[Sandy]

Works perfectly! Thanks!