思(おも)いっ切(き)りwith all one's strength, with all one's heart, resignation, resolution

夏休(なつやす)みは沖縄(おきなわ)で思(おも)いっ切(き)りはしゃぎたい！

For summer vacation, I want to really have a blast to my heart's content in Okinawa!

受験(じゅけん)が終(お)わったので、思(おも)いっ切(き)り遊(あそ)ぶつもりです。

Since the exams are over, I plan to play to my heart's content.

仕事(しごと)がとても忙(いそが)しい父(ちち)には思(おも)いっ切(き)り羽(はね)を伸(の)ばす時間(じかん)が無(な)い。

My father, who is very busy with work, doesn't have time to relax as much as he wants.

思(おも)いっ切(き)り力(ちから)を出(だ)した結果(けっか)、百(ひゃく)メートル走(そう)で一番(いちばん)になりました。

As a result of giving it my all, I came in first in the hundred-meter dash.

妹(いもうと)とは喧嘩(けんか)したくない。だって、思(おも)いっ切(き)り髪(かみ)を引(ひ)っ張(ぱ)ってくるから。

I don't want to fight with my younger sister. I mean, it's because she'll pull my hair as hard as she can.