Dave Kitson blasted a hat-trick inside the opening 30 minutes to preserve Reading's perfect home record this season and pile on the agony for Andy Hessenthaler.
The Gillingham boss saw his side ship three early goals for the second successive Saturday, following the previous week's 4-0 thrashing by Sunderland.
Following that defeat, Hessenthaler promised his side would not suffer another "spanking" all season, but this could have ended up as the mother of all thrashings.
Reading carved the Gillingham back line open time and again in the opening period, and could have gone in five goals to the good at half time.
Kitson grabbed his first with just fifty-seven seconds on the clock, heading Paul Brooker's left-wing cross inside the near post, before two identically struck penalties completed his first-half hat-trick.
There were few complaints about the first spot-kick award after Ian Cox tripped Nicky Forster as he homed in on goal, allowing Kitson to ram home from the spot.
But Steve Sidwell's unconvincing tumble under Nicky Southall's challenge on 28 minutes infuriated the visiting fans and handed Kitson the chance to smash home to complete his first Reading hat-trick.
Forster could have rubbed salt into the wounds as Reading looked set to run riot in the second half. But the pacy striker was narrowly off-target with a trio of efforts in the space of three minutes.
Those misses, followed by Darren Byfield's 55th-minute tap-in, gave Gills a glimmer of hope as they finally found a foothold in a game which had previously passed them by.
Byfield side-footed home when Southall teed him up after a sweeping move orchestrated by Patrick Agyemang. Agyemang then nearly added a second when he thumped a low shot against the post after sprinting clear of the Reading defence.
Kitson also rattled the woodwork when his stinging shot smashed against Steve Banks' crossbar, but by then the damage had already been done by the former Cambridge hit-man's first ever senior hat-trick.
The result saw Reading shoot up to second in the table, behind Wigan Athletic, who today thrashed Sheffield United 4-0 at home.