You just insult the enemy even if you don't share a language, threaten the wolf cubs that suddenly appear, get in the way of the enemy without moving somehow.
Insults: The nice thing about insults is that they're often (but not always) more than just a word. They frequently are coupled with tone of voice, facial expressions, and body language. If someone calls me a bad word in a language I don't know but in a pleasant tone of voice, I'll have no idea I've been insulted. But if someone calls me a bad word in a language I don't know and at the same time glares at me, says it in an angry or disgusted tone, mutters it under their breath, makes a rude or lewd gesture, spits, turns away sharply, sticks out their tongue or waggles their fingers in their ears--I can usually figure out I've been insulted.
Wolf cubs: The
actual example (assuming this is the correct one) doesn't say the cubs suddenly appear. They could have been part of the narrative all along. If the DM said "eight wolves step out of the bushes and surround you, snarling" then yeah, I could see not allowing someone to loom over cubs--the DM has established that there are eight (8) wolves, and that they're all actively engaged in the adult activity of ambushing player characters (cubs will be at home with mom). But if the DM said "eight wolves of various sizes and ages step out of the bushes" or "you stumble into a wolves' den, and eight wolves stand up and snarl at you" and the player says, "are there any cubs around? I want to loom over them threateningly," then sure--it's reasonable to assume that "various sizes and ages" means that some are cubs, and it's reasonable to assume that in a wolves' den, there would be cubs around.
But! I see that a post later you talk about mindless undead or constructs. Well, that's a completely different thing that has nothing to do with the power and everything to do with the choice of enemy. I searched for the power name and I found this description for Come And Get Me:
While raging, as a free action the barbarian may leave herself open to attack while preparing devastating counterattacks. Doesn't say you have to do anything
to the enemy; you're just leaving yourself open to the attack. And I think it's reasonable to assume that mindless undead or constructs would have been programmed to go after a particular type of target first: closest, largest, smallest, most armored, least armored, etc. You the DM don't have to actually decide what that programming is ahead of time (unless it's really important to the adventure), so if the barbarian steps up and uses that power,
then you say that something about the barbarian triggers their movement.
Getting in the way without moving: I can't find the original post for that, but "moving" in D&D typically means actually
moving, as in from point A to point B. If the Bad Guys are within reach of me or my weapon, I can definitely get in their way without leaving my space.