New scientists twitter competition led to more than 500 tweets regarding this subject and you can find top ten tweets that tried to explain what it exactly is. Here we go.
Timeless energy, / all dressed up, no place to go: / had to create space. / - #BigBang #haiku #sci140 - haiQ
God said delB=0 etc, & then light (sym breaking), separation light from darkness (recombination), man created from dirt (evolution) #sci140 - dmadance
#sci140 starburst, molecule, amino acid, protein, cell development, cell division, sex, technology, war, religion, OK magazine. - jonotrumpeto
@newscientist #sci140 Antimatter and matter duke it out. Matter wins 1 billion and one to 1 billion. The matter left expands and makes us. - zeroentropy
@newscientist .<∞ #sci140 - yanikproulx
#sci140 A place for everything, and everything in one place. Then -- kaboom, everything all over the place. - tui4
@newscientist The Big Bang: the moment the universe vanishes when extrapolating its expansion backwards into the past #sci140 - hubi1857
For t<0 some say there was no matter, others say it does not matter. For t>0 its a matter of life and death - as a matter of fact #sci140 - thebeerhunter
an argument between the 9th and 10th dimensions overspilled into the 1st, 2nd, 3rd and 4th. #sci140 - AlexStavrinides
The Big Bang: Basically a ballooning of bosons, belatedly bloating into our beautiful universe. Brought to you by the letter 'B'. #sci140 - CoyoteTrax
What do you think or in other words, can you tell in 340 characters what it is?