Convert YYYYMM to MMMYY Basing on this SO question.
Challenge is rather simple: given a date period in the format YYYYMM output it in the format MMMYY.
Rules:

The input will be a number or a string exactly 6 characters long, consisting only of digits.
Last two digits will be between 01 and 12.
Output must be in the form MMMYY, where MMM represents uppercase three-letter code for the month (below) and YY represents two last digits of the YYYY part of the input.

List of months with corresponding code:
MM    MMM
01    JAN
02    FEB
03    MAR
04    APR
05    MAY
06    JUN
07    JUL
08    AUG
09    SEP
10    OCT
11    NOV
12    DEC

Examples:
Input     Output
201604    APR16
200001    JAN00
000112    DEC01
123405    MAY34
Python 3, 70 bytes

from time import*
lambda s:strftime("%b%y",strptime(s,"%Y%m")).upper()


This uses the built-in strftime and strptime functions.

For 1 byte more, here's a version which parses the string manually:

lambda s:" JFMAMJJASONDAEAPAUUUECOENBRRYNLGPTVC"[int(s[4:])::12]+s[2:4]


This encodes the month names in an interesting way (thanks to Henry Gomersall for saving a byte).