Hi Irene, it's a strange sign! up can be used as a verb, like in this case (m-w.com) The meaning could be to make it a bigger, better, more expensive birthday. Maybe the most confusing part is Paula, who's Paula? 😳

It means add value to the birthday, improve it . Up your game Improve your game

Up the x can also mean support and aid the x. but I don't think that's the meaning here.

Hey Irene, The shopping mall Plaza Mar 2 is celebrating its 21st birthday. On their website they have the slogans, "up the birthday and "up the sorteo." Perhaps they are targeting more tourists by throwing in some English. If you "up something," you increase it. 1. If you up the volume on your computer speakers, you might hear me better. 2. They've upped the prices of groceries this month. I wouldn't add the expression "up the birthday" to your English vocabulary; it doesn't sound natural. Can we up birthdays? No, not really. It takes a whole year and this lottery (sorteo) is happening now. We can infer that they mean increase the birthday fun and the celebrations. The ad campaign is also playing with the word "up" in a few different ways. They have a raffle for a hot air balloon ride, "up the sorteo: gana un viaje en globo para ti y un acompanante." If it was a North American poster, I would say the advertisers are tapping into feel good moments of popular culture. "Up, Up and Away" is a Grammy award winning song from the late 60s. The phrase comes from Superman movies, but the song is about hot air balloons. Feel like Superman, a superhero, win money, win prizes, win the lottery, win their raffle, feel the freedom of flying and floating through the sky. Haha. Yeah, who is Paula? Paula, I would guess, is a celebrity in Spain or Europe? Perhaps connected to their advertising campaign? In this specific case, it wouldn't be "Paula, up YOUR birthday" because it is the shopping mall's anniversary. The main campaign message is an imperative command to encourage shoppers to spend more. The more you spend, the more receipts you collect, the more chances you have to enter their draw and win. Thanks for posting the photo and providing some context. Robert and Terry have great answers, too. There are many ways that "up" can be used as a verb, phrasal verb or idiom.

Robert provided good information. It's colloquial slang for sure. I have heard it used often in North American English. The phrasal verb "give up" or "give it up" has more than one meaning. One meaning for "give it up" is to yield or relinquish something. The term evolved into expressions like "up the 'za" meaning "give me a slice of pizza." "Up it!" This one can be in reference to so many items. I tend to think that "up the birthday" could mean "pull out all of the stops!" Make it a great birthday, Paula! I have only touched on this phrasal verb usage. It's one of those native English-speaker experiences that breaks the rules of grammar, but doesn't sound weird. Anyone else?