@oristarA,
The capitalisation suggests it is a headline or title. As discussed before, normal rules are often ignored in such writing. As a sentence it is crude and rather badly punctuated, (comma after exclamation mark and no period at the end) more suited to conversation that written English. In this case I think "Gulp!" is an onomatopeic interjection which is intended to convey the idea of swallowing a drink. I think the writer is thinking of beer or soft drinks which are often gulped (swallowed in larger amounts at a time) rather than wine or stronger drinks which are sipped or merely swallowed. Also sometimes people humorously say (or write) "Gulp!" to convey the idea of swallowing convulsively in fright, e.g. at the sight of a ghost. Maybe the writer intends to conflate these two ideas.
It is not the gulping of the drink which might make a person ill (or "sick" as Americans say) but the application of the mouth to the rim of a shared drinking vessel such as a glass or cup which makes ingestion of another (infected) person's saliva more likely.
Compare to this:
How, Bang! You Hurt Your Thumb
While Nailing Wood, Be Careful With The Hammer
Or this
How, Tick! Tick! Tick! A Noisy Clock Can Keep You Awake
When Buying A Bedroom Clock, Choose A Quiet One