I'm having a hard time finding an euphemism. Poli's examples all imply stealing, except "hacer una comprita", which I'd never heard before, but it's fabulous! I love it.
In some old newspapers you may find "apoderarse de lo ajeno" (to seize what is not yours), and about common thieves, you may find "amante de lo ajeno" (a fancier of what is not theirs).
Someone around me is suggesting these expressions (they might not be too common):
· Hacerse con algo (not slang; to get something by means of a ruse or to steal it)
- Me hice con los documentos para que nadie los encontrara. (I managed to conceal the documents and took them away with me so nobody would find them.)
- Los asaltantes se hicieron con las armas de los policías y se escaparon. (The robbers managed to deprive the cops from their arms.)
· Bailarle algo a alguien (slang; to steal without you noticing or to swindle someone out of something)
- Me bailaron el celular en el autobús. (I didn't notice when they stole my phone.)
- A José sus hermanos le bailaron su herencia. (The siblings cheated to get José's part of the inheritance.)
· Limpiar (slang; to "cleanse")
- El ejército pasó por el pueblo y lo "limpiaron". (They took everything with them.)
- A Pedro le dejaron limpia la cuenta del banco. (Pedro's bank account was hacked and they stole all his money.)
- Me asaltaron en el callejón y me dejaron limpio. (I was robbed in the alley and they left nothing on me.)