You know your rockets are REALLY big when...

[MedwedianPresident]

...you use 0.625m boosters as stage separation motors.

 

Your turn.

[Voyageur]

When the whole time you're building it, you wonder if @Whackjob would approve or simply laugh at it in mockery.

[dangerhamster]

When upon clicking to move a Kerbal to a different module you are presented with a "use railway" option.

[Zeiss Ikon]

When you have to embed the booster nozzles in the floor to add bits to the command pod because you can't shift view any higher within the VAB.

[MinimalMinmus]

When the launchpad literally suicides at launch

[Firemetal]

When you use the Hangar Extended mod.

Fire

[cratercracker]

When rocket is using kickback engines as booster seperators.

[septemberWaves]

When your first two stages are so tall that you can no longer see the payload or third stage in the VAB.

[ZentroCatson]

When lighting the engines causes a medium earthquake.

[StubbornJeb]

when you fire the engines and the rocket causes Kerbin to tilt its axis 

[InterCity]

When you need a transfer stage to get your kerbals from the CSM to the lander.

[joacobanfield]

When the rocket appears to have more surface area than the KSC.

[Hotaru]

When your measure of system performance goes from "frames per second" to "seconds per frame."

[WWEdeadman]

When you arrive at Gilly and IT starts orbiting YOU.

[vitekc45c]

When MK3-long tanks start to look small.

When you actualy build something larger than Whackjob.

When 1.5k parts is a small number.

When you measure your crafts weight in kilotons.

[W. Kerman]

When, before launching your craft, it destroys half the KSC.

[StrandedonEarth]

  On 2/26/2017 at 11:43 AM, MedwedianPresident said:

...you use 0.625m boosters as stage separation motors.

Expand  

Not enough.

  Quote

.... when you use RT-10s as sepratrons.

Expand  

Not enough.

  On 2/26/2017 at 12:28 PM, cratercracker said:

When rocket is using kickback engines as booster seperators.

Expand  

Sorry.

... When you have to use Rhinos!

Mad props to anyone who gets the reference.

Edited February 26, 2017 by StrandedonEarth

[MinimalMinmus]

When colliding Gilly prompts the message:

1 y, 65 d, 3:20:56: Gilly crashed into Gigantorix2000 and was destroyed

[cratercracker]

When your computer melt at the same temperature as fuel in engines.

[Allocthonous]

When you go EVA, and all your science reports list the biome as "In orbit around *Vessel Name*"

[Tex_NL]

When you're no longer impressed by any of the 'serious' answers in threads like this.
The troll answers just get ignored.

[CaelumEtAstra]

When you can lift several-hundred-thousand ton payloads with Delta-V to spare.

When the frame rate is better measured in frames per minute.

[TimePeriod]

When the game crashes before you even get to the launch-pad.

[Spacetraindriver]

When your computer blacks out.

[MinimalMinmus]

When you have to say "MOAR CPU" to be able to process your rocket