to swallow hastily, to gobble up
噋 centers on eating quickly and greedily: swallowing hastily or gobbling up food without pause.
噋 combines 口 (mouth) with 敦, which likely contributes the sound and may relate to the idea of earnest or forceful action, suggesting eating with urgency.
The mouth radical 口 beside 敦, which looks like someone earnestly working, suggests a mouth working hard to swallow food quickly. Picture a person gobbling up a meal with intense focus.
For トン, imagine a ton of food being swallowed hastily: ton -> トン, and the mouth gobbles it all up.