To describe something ultra best. Instead of saying something like, "that was awesome", or "wow that's the coolest thing I have ever seen". Also, can be used to describe besting something, or dominating it. Opposite of the word being 'worstachire'.
1 Mike - "dude, that chick I met the other night at the bar

asked me out!"

Seth - "bestachire!"

2 Matt - "I just bestachired Worms Armageddon online!"

3 Thomas- "My worsties day just got BESTACHIRE!!"
by mrsavage2020 October 23, 2011
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