The Speaker will direct an MP who has used unparliamentary language to withdraw it. Refusal to withdraw a comment might lead to an MP being withdrawn from the house, if necessary by force.
List of Unparliamentary Terms
blackguard
coward
git
guttersnipe
hooligan
hypocrite
idiot
ignoramus
liar
pipsqueak
rat
swine
stoolpigeon
tart
traitor
sod
slimy
wart