warikomu
1.

To forcibly enter a line or group, disregarding established social norms or etiquette, often leading to interruptions or disruptions in ongoing interactions.

2.

To intrude into a conversation or setting at an inappropriate moment, asserting oneself without consideration for the current participants or their exchanges.

3.

To reduce the value of a market price by entering or influencing it in a way that pushes it below a certain threshold.

Example:

人の話に割り込むのは失礼だぞ。