Death Knight trick - Have a Ghoul as Blood Spec

I've known about this for a while  so here's a tutorial:

Step 1) Have dual spec, Primary Blood and secondary of Unholy

Step 2) Switch to Unholy and summon a ghoul

Step 3) Open up your battleground que, select your role as tank and que up

Step 4) When you join the BG you will be in Blood but you will still have the ghoul (this doesn't work for AV for some reason)

Step 5) If you want to keep the ghoul, don't die in the BG, the ghoul will still be with you when you exit the BG (especially fun to take in to Ashran)