Wassup mah homies LOL. Are you tired of looking at this all the time?:

Yeah, I know, I was tired of that screen too!
If you want to know how to change it, then this tutorial is for you! c;
-StephanieBoo

After I changed it:
(I can't screenshot the one for gimp 2.6 anymore, because it's gone. :c I really liked it too. I had to remake it because I lost the pic.)

2.6:

2.8:

1. Create a new image with the dimensions:
275x400 (GIMP 2.6)
557x346 (GIMP 2.8)
{Make sure you're using the correct dimensions, or else it won't work!}

2. Add anything you want onto the blank canvas! You can do whatever you want, as long as you don't change the size! ^^
Follow your heart's desires...

3. Ok, this is the part where you need to pay extraa atention.
When you finish, press Save As (For Gimp 2.6)
If you're using Gimp 2.8, then go to file>export to (They changed things up a little bit...)

Do not save it in your pictures folder.

For Gimp 2.8:

Computer>Your harddrive file>Program Files>GIMP 2>share>gimp>2.0>images

For Gimp 2.6:

Computer>Your hard drive file> Program Files (x86)>Gimp 2.0>share>gimp>2.0>images

(took the pic from another tut, since I don't have 2.6 anymore. credits to her! ^^)

If you go into the "images" folder, you will see three pics in there already:

Delete the original gimp-splash.
Save your image here.

SAVE AS:

gimp-splash.png

Now, restart your gimp, and instead of the old splash screen, you should have your new, customized one!

If you have any questions, leave it in the comments or PM me.

Hope this helped!

If not, i will cry waterfalls :(