Tuesday Riddle! Solve it and win a copy of The Arrival

Okay I'm in a state of shock right now… Seriously I'm speechless and that happens rarely people..
I got sent a tweet saying
SARARUEFORREAL @Dmslinadrtydrss - I'm totally gonna download ur book to my iPad :)
Which made my jaw hit the floor and I replied
@SARARUEFORREAL ...*gulp* ... okay I know this says Sara Rue for real but is it!?!? IS it???!!! *cue hyperventilating*
And then I got this direct message
Yep - my fiancé saw some or ur tweets about the book. I have a shoot this week but plan to start reading it after things calm down a bit :) Direct message sent by Sara Rue (@SARARUEFORREAL) to you (@DmslinaDrtyDrss) on Mar 29, 7:19 PM.
So I meant to say stuff on this blog but I can honestly say it's totally gone out of my head.. I'm swinging between extreme delight and the urge to squeal like a 16yr old (..okay I may have indulged myself there…) and utter terror she'll hate it… Actually no that's kinda behind the stunned mullet expression at the moment.
Here's the riddle
You have a barrel of oil, and you need to measure out just one gallon. How do you do this if you only have a three-gallon container and a five-gallon container?
Take care all!Nic The Arrival, only $3.99 on Amazon or UK Amazon or $3.99 on Smashwords Buy it today!