Killstreak Bonk Helm
If there is a 'universal' Specialized or Professional Killstreak Kit attached to the Bonk Helm, the sheen will only appear on the soda cans. This is because the Bonk Helm's soda can models are ripped from the weapon, which supports having sheen.
There are 33 known instances of this item (27 in Unusual and 6 in Vintage quality).
Source
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Unusual Specialized Killstreak Bonk Helm
Team Fortress 2 Level 23 Helmet
Paint Color: A Deep Commitment to Purple
★ Unusual Effect: Roboactive
Sheen: Hot Rod
Killstreaks Active
When drinking one radioactive beverage at a time is not enough.