In case you're wondering what's a Pérola:
And about their origins:In literal terms, Pérola is Portuguese for pearl.
In figurative terms, Pérola is also used to describe "something curious or interesting"
And from that figure of speech, the Portuguese Dragon Ball fanbase gave the name Pérola to all the local references, jokes and comical situations added in the European Portuguese dubbing of the franchise.
There are two different versions about the origins of the pérolas:
- The first one, according to Henrique Feist (Goku's VA), is that when they were recording, some dialogues turned out to be shorter than they were after being translated from French (like most of Europe, the source version was the French AB dub) to Portuguese, so it was decided to make some adaptations (the pérolas themselves) for lip sync reasons.
- The second one, according to João Loy (Vegeta's VA) is that SIC requested the dubbing staff to record the dub to be more family friendly in order to tone down the violence.
It should be also noted that António "Tó" Sémedo (the late voice director of the franchise's dubbing until GT and Narrator's VA) was mainly a comical actor. So it wouldn't be weird to suggest that background of his played a role in the dub's localization.
[TBD]
Saiyan Saga
When Vegeta is about to fight Goku in the desert area, he says the following:
Vegeta: "Muito bem, será melhor que o Big Show SIC"
Translation: "Very well, it will be better than Big Show SIC"
Explanation: Big Show SIC was a talk show hosted by João Baião, Jorge Gabriel and José Figueiras, that ran from 1994 to 2001 on SIC, the TV channel that aired the Dragon Ball franchise in Portugal until the episode 104 of Dragon Ball Super because SIC wasn't longer interested to air the franchise and Biggs eventually picked up the broadcasting rights.
Planet Namek Saga
When Vegeta is hitting Ginyu (before he switched bodies with Goku), he says the following:
Vegeta: "Ay, um-do-li-tá!"
Explanation: A Portuguese children's song usually sung before starting to play games.
Androids & Cell Saga
When Goku is about to teleport from Kami's lookout, he says the following:
Goku: "Agora silencio que vou a cantar o fado."
Translation: "Now be quiet I am going to sing fado."
Explanation: Fado is a music genre from Portugal. Its origins date back to 1820s in the capital city, Lisbon.
The pérola also makes reference to musicians when they demand their audience to be quiet, so they could start their show.
Majin Buu Saga
When Videl is being brutally beaten up by Spopovich, the Tenkaichi Būdokai announcer starts saying the following:
Announcer: "CALMA VIDEL" (x3)
Translation: "CALM DOWN VIDEL"
Explanation: A weird attempt to tone down a brutal scene.
When Yaakon shows up for the first time, Goku says the following
Goku: "É a Miss Portugal '97!"
Translation: It's Miss Portugal '97!
Explanation: Random comparision between Yaakon and Icília Berenguel.
During the 25th Tenkaichi Būdokai events, there's a little scene with a man of the tournament staff dishwashing and singing the following:
"Água fria, da ribeira"
Translation: "Cold water, from the stream"
Explanation: A verse (0:30) from Aldeia de Roupa Branca , sung by Beatriz Costa

[TBD]

If you feel there's something missing, outdated or wrong, don't hesitate to tell me.Battle of Gods Saga
In the Kaioshin planet, when the Elder Kaioshin hands Shin a magazine with a topless girl on the cover, he says the following:
Elder Kaioshin: "Toma, é Mária Leal"
Translation: "Take it, it's Maria Leal"
Explanation: Maria Leal is a Portuguese singer who became known after she sang her first single "Dialetos de Ternura" on TVI's show, Você Na TV! (You on TV!) and her (only) resemblance with the girl on Elder Kaioshin's magazine is that they both are blondes.
Universe 6 Saga
When Vegeta goes Super Saiyan Blue during his match against Kyabe, he says the following:
Vegeta: "Super Guerreiro Azul Wanda Stuart"
Translation: "Super Saiyan Blue Wanda Stuart"
Explanation: Wanda Stuart is a Portuguese singer, TV host and producer who has her hair dyed blue.

EDIT #1: Added another concept of the word "Pérola" and expanded more about the "Fado" pérola (thanks Luso Saiyan)
EDIT #2: Added "Big Show" pérola on Saiyan Saga and "Calma Videl" pérola on Majin Buu Saga.
EDIT # 3: Added origins of the pérolas.