UU Game Terminology - Simultaneously
Adverb: in a way that is simultaneous (= happening or being done at exactly the same time):
During gameplay many effects will occur Simultaneously, these effects do not occur in a linear sequence but are happening at the very same time. The action to perform these effects are performed as a sequence for the purposes of the interaction of gameplay components.
The Beginning of turn phase...
If any cards in your Stable have an effect that states, "If this card is in your Stable at the beginning of your turn," they are triggered now. If you move to your Draw phase without triggering an optional triggered effect, you can no longer trigger that effect this turn.
These effects occur Simultaneously you do not have the option to disregard any, they all "trigger" regardless of the outcome.
and 
Both of these cards have optional effects but both regardless of choosing those options will still "trigger" at the Beginning of Turn. Both have the conditional argument of choice and that argument ceases to exist when the player chooses not to use it. (This behaves in a similar way as a requirement would, you are required to make a decision to use these abilities or not).
If one or both effects are chosen to be performed an effect chain is created; If both are chosen:
Unicorn Lasso requires a unicorn card to be chosen to STEAL , Glitter Bomb requires a Sacrificed and a target to Destroy
OR
Glitter Bomb requires a Sacrificed and a target to Destroy, Unicorn Lasso requires a unicorn card to be chosen to STEAL
All effects in the chain are happening at the same time, both statement are performed as written one way or the other. Then the next link is performed.
The lasso'd unicorn is moved into the Stable and the Glitter Bombed card is destroyed. "at the same time"
OR
The Glitter Bombed card is destroyed and the lasso'd unicorn is moved into the Stable. "at the same time"
The Beginning of Turn chain effect has now concluded, however different "new" effect chains may have been created when the stolen unicorn left the Stable, When the Glitter Bomb sacrificial card left the Stable, when the stolen unicorn enters the "new" Stable or when the destroyed unicorn left the Stable.
These effects are links in a chain, a player does not get to choose which links or card to do as they wish.
The player does not have the ability to Lasso the unicorn into their Stable to then Sacrificed it to the Glitter Bomb.
TIP: If the card is not in the stable when the turn started, how can it be sacrificed?...(It cannot.)
NOTE: The Lasso'd unicorn can be sacrificed as any other card in the stable can be, just not to another Beginning of Turn effect.
Continuous Effect...
and 
