"Hashtag" introduces a search phrase. The search phrase is "Wear a bib". Normally babies wear bibs when they are eating. This keeps their clothes clean. I would guess someone is being sarcastic and is making fun of someone who is eating messily like a baby, by suggesting that they need to search for, buy, and wear a bib.

hashtag equals the '#' sign for Twitter and/or social media on the internet. It looks like your sentence was used in a comedy show created within the past few years. 'Get a bib' while drooling could mean that they are a messy eater or if it was a guy staring at a female then it was a joke to stop staring (and drooling while looking at them). There is no significance of the statement other than it was a joke.