CBS explains Season 8 Episode 5 of The Big Bang Theory as:
Amy and Bernadette accuse Penny of being a “buzzkill” after she gets an email from work during their Vegas weekend. Meanwhile, the guys try to invent something cool, but only come up with new ways to procrastinate
Here’s a sneak peek into the Top 5 spoilers for the episode.
1. The Girls Go to Vegas for the Weekend

(CBS)
According to Big Bang Wiki, Leonard gives the girls the idea when he asks Penny if he can have a physics weekend without her.
The trio plan a girls’ weekend to Sin City.
2. Penny Stays in to Work

(CBS)
While they’re at the hotel getting ready, Penny gets a work email which causes her to stay in and study for her new job.
Bernadette, who got Penny the position in pharmaceutical sales, is proud of her dedication.
3. Bernadette & Amy Get Drunk
From the clip above, we see the drunken exchange between the scientists.
Amy compliments Bernadette’s body. “Look at you, your body’s banging,” she says. When Bernadette gets embarrassed, Amy responds with, “We’re always talking about how hot Penny is.”
4. The Boys Work on an Invention
In the lunch room, the guys decide that they are often distracted by their girlfriends and set out to invent something new with them away.
In the clip above, Leonard excitedly announces, “OK, let’s focus. The girls are gone, we have 48 hours, there are no distractions. Let’s change the world.”
However, instead of working, they just want to have fun and play Pigeon Ping Pong and watch Back to the Future 2.
5. The Ladies Head to a Strip Club & Are Hungover the Next Day

(CBS)
Penny is stone cold sober and has to deal with the Bernie and Amy in the club.
The next morning, Penny is standing over their bed, ready to head to the pool, but they are obviously hung over.