Be queuing up
Definition 1 of 2
Pro Tip 1/3Physical Lines
Used when referring to people standing in a real line. 
People were queuing up for hours to see the new exhibit.
Pro Tip 2/3Anticipation
Indicates people are waiting with excitement or impatience. 
Fans are queuing up outside to meet the author.
Pro Tip 3/3Not Always Literal
Can be used when there's an implied, not visible, sequence or wait. 
Students are queuing up in their minds for graduation day.