What is short shrift?

Answer 1

The English word shrift, taken by itself, means "confession"

It comes from the verb "shrive", an old word for making a confession and receiving absolution from a priest (or for the other side of the transaction -- the priest's hearing the confession and granting absolution). When the process is complete one is "shriven", that is "absolved of sins".

As for "short shrift":
A condemned criminal at one time would be sent to the gallows immediately after sentencing, and given a chance to make confession before being executed, but only a very brief time. Thus he only had the opportunity to make a brief confession, that is, a "short shift".

See this use in Shakespeare's play Richard III,
"Dispatch, my lord; the duke would be at dinner:
Make a short shrift; he longs to see your head."

http://www.phrases.org.uk/meanings/short-shrift.html

From this use -- of giving someone only a brief time for confession and absolution comes the modern sense of giving someone/something scant attention or making short work of something (esp. something serious that would seem to deserve a bit more attention)
http://www.thefreedictionary.com/short+shrift

The other modern expression in which you might hear a form of this word is "Shrove Tuesday" (though many nowadays prefer "Mardi Gras" which has a very different sense). Shrove Tuesday is the last of the three days of "Shrovetide" ("tide" having the sense of "time"), the period during which one is traditionally to go for confession before Lent begins on Ash Wednesday.
http://www.thefreedictionary.com/shrovetide

Compare the following recent use of this verb:
"Tomorrow is Shrove Tuesday. At the cathedral, the Dean announced that if anyone wished to begin Lent by being shriven, they were welcome to present themselves sometime on Tuesday, and one of the priests would be glad to hear their confession."
http://cassandrapages.typepad.com/the_cassandra_pages/2006/02/shrove.html

It is generally explained that this verb is related to Latin scribere, "to write" (and German schreiben, noun form "Schrift" = "writing") and explain it as first meaning "writing or prescribing a penalty" (applied to the confessional this would refer to the imposing of penance)
http://www.randomhouse.com/wotd/index.pperl?date=20010509

But it may not be so simple. Compare the following etymology:
"OE. shriven, schriven, AS. scrivan to shrive, to impose penance or punishment; akin to OFries. skriva to impose punishment; cf. OS. biskriban to be troubled"
http://www.bibliomania.com/2/3/257/1210/24054/1.html

Answer 2

Giving someone "short shrift" means blowing them off and rejecting them. For example, if I ask a question on here and someone answers with "U r stupid go away" - they've given me short shrift.