You might have been celebrating this occasion during the last week or so. It’s not celebrated much in English-speaking countries, except for Notting Hill and New Orleans, but in much of Continental Europe and South America, it’s quite a big deal. The celebrations occur before the Christian period of Lent: 40 days of abstinence and/or fasting before Easter. Carnival is a catharsis, one last big blowout before the austerity of Lent. While we do use the word carnival in English in a general sense to refer to a travelling circus or funfair, the word has its origins in the religious context. It seems to come from the Latin phrase carne vale, meaning farewell to meat, with people indulging themselves in as much meat as possible before giving it up for Lent. The phrase can also be translated as farewell to flesh, leading some to take that as a cue to get physical. And if they were planning on giving that up for Lent, why not? They could also point the word carnal as having a similar etymology to justify themselves.
But as I said, Carnival isn’t celebrated so much in the English-speaking world. It’s probably hard to get excited when the last day before Lent is known as Shrove Tuesday. Shrove comes from the word shrive, meaning to hear a confession or deliver penance. Shrive in turn from the Proto-Germanic skriban, meaning to decree or write (also the origin of words like script and scribe. Which kind of makes sense: putting something in writing makes it seem more solid, more real. Mardi Gras, now that sounds much more fun, largely because it’s French, but it probably doesn’t sound so attractive when you consider that it means Fat Tuesday.
As for the word Lent, it comes from the West Germanic langitinaz, meaning long days or lengthening of days, which makes sense as it occurs in spring, but it’s probably not what you want to focus on when you’re fasting. And perhaps you are fasting, as it’s now Lent, and many Christians worldwide still give something up. Give up meaning relinquish, pass something on to someone else. Interestingly, give up is basically a direct translation of surrender, coming from the French sur (on, above) and rendre (give). Which is what you’re doing when you give something up, surrendering it, perhaps temporarily.
So if you are giving anything up for Lent, hopefully you got it all out of your system at Carnival!