ABREAST

ABREAST       /əˈbrɛst/:  

1. Side by side and facing in the same way
2. Alongside or level with something

Memory key

Seeing it AB are EAST. That means and two people A and B are moving in same direction.

Example 

The two people walked abreast along the road.




Note : 

Another memory key if you don't see it as obscure language.

Seeing it as A+Breast The physical appearance of both of them may be level and faces in same direction.