Tonight, U2 play the first of their four sold-out concerts in Dublin's 3Arena. And what did the lads do to prepare themselves for the gig? 

They went out for a pint of Guinness, of course!

The lads spent a few hours in Peter's Pub on South William Street, and surprisingly, went pretty much unnoticed until they posted a photo onto their Twitter account. 

They captioned the snap of the four pints, "The boys are back in town," which made fans even more excited about tonight's gig. 

And as for who the photographer was? Many fans are claiming it's Bono as they're trying to take close-ups of the shared photo. 

Either way, it's a brilliant idea to let their fans know the boys are back on home turf.