Pretty please?

No.

Perhaps I better start at the beginning. Speakers of many languages are taught, when they are young, to use please and thank you to be polite. So it comes as a surprise to many people when they find out that things are not always that simple in other languages and cultures. Let me give you some examples to set the scene before we move on to Gaelic.

In Icelandic, there is a phrase for thank you: takk fyrir. But perplexingly (for some people anyway) the most common response to someone saying takk fyrir is takk takk. It's like saying thank you and someone responding thanks thanks. Amusingly, this is also what happens in Chichewa (a language from Malawi) where you say zikomo for thank you and people respond by saying zikomo back at you.

Half way round the globe, learners of Cantonese are faced with the headache of two words for "thank you". One, 唔該 (mgōi) is the more generic one and 多謝 (dōje) is mainly restricted to thanking someone for a gift. Confusing for many foreigners too is the fact that even though Cantonese society treasures politeness, especially towards older people, phrases that might translate as "please" are rare. For example, if I was asking my grandmother for permission to stay out a bit longer to play, I would not use "please". I might use a particle at the end of my question to make it sound "little" and most certainly I would address her with the proper vocative particle and her "rank" (it sounds weirder than it is, it's really not unlike calling someone Sir or Madam in English). But no "please" as such.

Which neatly brings us to Gaelic. While there are several words for saying thank you (depending on politiness and your dialect), there is no word for "please". Yes yes yes, I know, you've watched Speaking our Language or done some online course where the phrase mas e do thoil e or the politer mas e ur toil e appears for "thank you". Honestly, that's just English-inspired nonsense. These two phrases makes most native speakers want to hide under a blanket or consider violence, at best, they grate on their ears.

The phrase does exist traditionally but it is used for a different purpose. Think of costume drama and some servant girl going "Might I have the afternoon off next Saturday if it pleases Sir?". That's the kind of situation where you might hear (or rather have heard) mas e do thoil e. But not in a shop in Ness or the ferry to Mull.