"Butt in line" vs "cut in line" vs "bud in line"?

Solution 1:

As badroit notes, queue is more common in British Engish whereas line is more common in American English in non-technical settings.

A queue-jumper cuts in line, in which cut may be interpreted as the sense of trimming or dividing depending on whom you ask; Merriam-Webster lists this sense as a separate meaning:

cut: intransitive verb 5. to advance by skipping or bypassing another. cut to the front of the line

To butt in is to intrude. In queueing cultures, cutting in line would be rather rude, and could be described as butting in into line, especially if one is literally physically butting, i.e. thrusting or pushing headfirst.

Bud in is probably an eggcorn for butt in.