For unix you can use termios.tcflush
from termios import tcflush, TCIFLUSH
import time,sys
a = raw_input("first input ")
b = raw_input("second input ")
time.sleep(5)
tcflush(sys.stdin, TCIFLUSH)
a = raw_input("third input ")
b = raw_input("fourth input ")
~$ python foo.py
first input 1
second input 2
33
33
third input 3
fourth input 4
termios.tcflush (fd, queue)
fd. , : TCIFLUSH , TCOFLUSH TCIOFLUSH .