Start hitting on them with really bad breath.
Top #1 turn off in majority of surveys show bad-breath has the best olfactory memory and unpleasant negative subconscious retention factor.
Do not do this if you are Super Attractive - it will back-fire, this technique is for average looking people only :P
blows mouth gas into guests the moment i want to be left alone
well if you're the host that invited the guest they might tolerate it longer, the research was based on strangers :P