Many of the characters in BFDI, depending on the object, have had their own 'OMG' moments in which they state "Oh my" and then something relevant to their "God", which is something related to their object form, for example Pin's "god" is a Pin Factory, which created her.
Some characters even have 'WTH' (what the heck) moments, like Snowball (What The Flake) and Match (What The Wood Sickle).
FlowerIn Insectophobe's Nightmare 2, Flower states her OMG as "Oh my Gardener!"
Woody is yet to have and most likely never will have an OMG moment, since he doesn't talk much.
Teardrop will probably never will have an OMG moment since she can't talk.
Golf Ball is yet to have an OMG moment. But if there is one, it might be: "Oh my dimples!" or "Oh my Place Where Golf Balls are Created", or for short, "OMPWGBAC!"
In Season 1 Coiny's OMG moment was "Oh my Midge" or OMM.
Snowball's OMG moment was said at the biggest and final rejoining ceremony of Season 1 as "Oh my Snowflake!"
In Cycle of Life, she may have said "OMT", which may mean "Oh my Tree" but it may have just been an "OMG". Closed Captions say "OMG", but they weren't set by hand.
Match is the first to say OMG or a related word like OMQ, OMW, OMZ more than 10 times even 20 times.
In Fortunate Ben, when Liy change her appearance Pen said "What the flip!".
David is yet to have and probably will never have an OMG moment, as he is usually seen saying his only catchphrase, "Aw, seriously?" or "NO!"
Pencil has an OMG moment, and it is "Oh my Tree" because wood comes from trees, and Pencils are made with wood. It has been used twice in both the BFDIA 6 Deleted Scenes video as well as Welcome Back.
Rocky was planned to have an OMG moment, but then jacknjellify decided to take away his ability to speak. It remains unknown if Rocky will ever say OMG.
Bubble's OMG moment is "Oh my Bubble Blower!", sometimes shortened to "OMBB!"
Also in Gardening Hero, she said "Oh my Go(i)sh".
Also in Barriers and Pitfalls Leafy said "OMZ", no one knows what it stands for though.
Nickel is the only character to say "Oh my God", in Episode 5d: It's a monster
Firey's OMG moment is "Oh my Oxygen!", used once after getting barfed on.
Firey in multiple episode's has said "Oh my gosh".
In BFDI Is Back (although not being canon), Firey used "Oh my spark" once for his OMG moment after finding that Bfdi is back.
Book's OMG moment is "Oh my Word", used twice.
Fries' OMG moment is "Oh my Potatoes", used twice.
In Welcome Back, Fries's other OMG moment is "Oh my tater", used once.
Gelatin's OMG moment is "Oh my collagen", used once in a video including BFDIA 6 deleted scenes.
In Four Goes Too Far it was considered to have Donut say something along the lines of "Oh Dear God", but was replaced with "This can't be real" because according to Cary they didn't want to have God in a BFB episode.