You know you overbuilt your rocket when...

[Kizarvexis]

...you use the last part of your lifter to make the transfer burn.

... and the circularization burn, ... and part of the landing burn, ... and you only stage because this part of the rocket was never meant to land.

This is EVERY rocket I send to Minmus.

[Steambirds]

You know your rocket is overbuilt when its orbital engine is a mainsail 'cus everything else is too slow for the 100 ton payload.

[Guest]

You know your rocket is overbuilt when its orbital engine is a mainsail 'cus everything else is too slow for the 100 ton payload.

I normally use Kerbodyne KR-L2s.

[Lichbane1401]

When you launch it and the engine sound blows up your stereo

[Tsevion]

When you're sad all you could find was a scrawny class E asteroid to bring home... and keep wondering where you can find a class F, G or H.

[Space.exe]

...You make a full tour around the kerbol system on your first stage.

[cantab]

When you have to strut your struts.

[Hary R]

When it blow up the entire ksc buildings just by siting on the launch pad:cool:

[Grover]

When your launch escape system needs a launch escape system... And consists of at least one jumbo orange tank

[Holyvision]

When you require more launch stabilizers than any other part.

[Sanguine]

When your rocket does a gravity assist around a black hole.

And it's periapsis is BELOW the event horizon.

[zekes]

when your replica rocket can carry ​several smaller replicas of the exact same rocket inside it.

[LostElement]

You know you've overbuilt your rocket when you have to use 5 NASA engines to push your Mother ship from Kerbin to Eeloo at a reasonable pace

[ExplodingRocketShips]

When your superfreighter crushes the launch pad upon physics loading

[bigyihsuan]

When your Jool flyby mission still uses your 3.75m orbit stage to transfer to Jool

[worir4]

When you try to launch, instead of just destroying the launch pad, you destroy the entire of Kerbin.

Also when instead of vernier thrusters for stability you use the large x4 NASA pack boosters.

[Spatzimaus]

When... never mind, there's no such thing as an "overbuilt" rocket. Ever.

[Kobymaru]

Colliding with Pol looks like this: http://i.imgur.com/VUfH7Ow.png

[wraith of vern]

...when your space station becomes a Duna mission.

[LABHOUSE]

Your last stage has a twr of 20... on kerbin.

[MGCJerry]

Your smallest RTG creates more energy than Kerbol.

[Trentendegreth]

when you hit space for launch, and the phone rings, when you return your interstellar... "mechjeb autostage"

[Sanguine]

When you decide to rename Asteroid Redirect Mission to Eve Redirect Mission... and redirect it into the orbit of Jool.

[Basilo1146]

When you have a septuple clamp o tron sr. bond as part of your design. And then 18 more docking ports on the two pieces it it connects.

[worir4]

When your engines ignite, Jeb looses his cool....

Also when you power up your nukes observers from other solar systems think they are witnessing the birth of a star.