People would be very hesitant to use their coins if they know what happened with Lazlo and that is the exact opposite of what merchants want to promote. 
Also I don't know what happened in the past on the Black friday day
Most merchants don't know that. There was spend so much bitcoin in that pizza, I think deal with that story behind it may cause tradition huge rise in one particular day instead of sales lol.
You might be right
So... lets choose other day for such happening. First block mining day? Or maybe halving day - do promotions and discounts every 4 years. Bitcoin are doing very well on Black Friday, but using coins for Black Friday specials might increase the coins in supply and thus decrease the price of the token, if the demand does not increase. You merchants love it when people spend their coins, but we hoarders hate to spend coins, without good reason.
Well, another big day would be the day when Satoshi first introduced Bitcoin to the world.
< 3rd of January when the genesis block was mined> 
