pig's snout; nose like a pig's snout
Refers to the actual snout of a pig, or a human nose that resembles one (often upturned with visible nostrils).
That kid has a pig-like nose, and it's her charm point.
snorting like a pig (while laughing)
Describes the snorting sound made when laughing hard; often used in the phrase 豚鼻になる.
It was so funny I laughed so hard I started snorting like a pig.
Standard kanji spelling.
Katakana spelling for the animal part, sometimes used for emphasis or in casual writing.
Compound of 豚 (buta, 'pig') and 鼻 (hana, 'nose'). The reading hana becomes bana due to rendaku.